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International audience; The boiling liquid expanding vapour explosion (BLEVE) is well known but not well understood. Some still argue about what comes first, the BLEVE or the vessel rupture. Some believe the BLEVE is triggered by some pressure transient inside the vessel and this causes a superheat limit explosion which causes the vessel to rupture. Others believe it is the vessel rupture by some weakening process that leads to the BLEVE. This paper will provide evidence that the latter description that is correct for most, if not all BLEVEs observed in practice. This paper describes small scale experiments of aluminum tubes that were weakened by machining a thinned wall area over a specified length. The tubes were filled to a desired level with liquid propane and then the propane was uniformly heated electrically until the tubes failed. The failure pressures ranged from 10 to 33 bar. The tube was instrumented to capture failure characteristics (pressure, temperature) and consequences: blast overpressure and imaging of the propane cloud and shock around the vessel; ground force under it; transient pressure and imaging of the boiling process inside the vessel. The work was done to improve our understanding of the fluid – structure interactions during the fire heat induced failure of a pressure vessel holding a pressure liquefied gas. We were specifically interested in the near field hazards including blast overpressure and ground force. This paper will focus on the early milliseconds of the process where the vessel begins to open and a shock wave is formed and moves out into the surroundings. The imaging reveals presence of a Mach shock at the exit of the vessel at the early stage of the opening. A chronology of the event also shows that the lead shock is generated early in the explosion process, and is long gone before the liquid starts boiling, arguing that vapour expansion is the main contributor to the first shock overpressure.

Fires may induce the thermal failure of LPG storage and transport vessels, leading to severe escalation scenarios. In the present study, an innovative CFD modeling approach was developed to investigate the thermal behavior of LPG tanks exposed to fires to support the prevention of catastrophic scenarios. For the first time, several data-sets were used to assess the model predictions considering different vessel scales, fire geometries and configurations. Comparison with experimental results demonstrates the predictive capabilities of the approach. The model allowed analyzing the role of different key phenomena, such as: the effect of free convection and thermal boundary layer forming in the near wall region, the thermal stratification, both in the liquid and the vapor phases, and the liquid thermal expansion. In addition, the influence of the vessel geometry on such phenomena was investigated. The results obtained may drive the design of emergency response, improving the safety of hazardous materials storage and transport systems.

It is known that the passage of a strong shock wave in a moist atmosphere usually produces a condensation cloud that is briefly visible to the human eye. Weaker shocks such as those from boiling liquid expanding explosions (BLEVE) and vapour cloud explosions (VCE) may also produce such visible condensation clouds under certain atmospheric and lighting conditions. The Sunrise Propane accident in Toronto, Canada in August 2008 involving both BLEVEs and VCE gave clear evidence of this. In this age where video footage of an explosion incident is the norm (i.e. from the smart phone of a remote observer, or from a security video camera) it is very likely that there will be visual evidence of explosions. This evidence may include the size of a condensation cloud from a shock wave. This paper presents examples of such images along with a simple analysis that allows us to estimate the overpressure of the shock wave at the edge of this condensation cloud. In many cases we can also determine the distance to this shock overpressure from the video image. With this overpressure and distance data it is possible to estimate the energy of the explosion and the overpressure and expected damage at other distances. This could be very useful for accident analysis. Limited video footage of BLEVE tests is used to validate the method.

International audience; This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m−2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.

Fire protection of pressure vessels for transport and storage of dangerous goods is an active topic of research around the world. In many cases, organizations are conducting theoretical analysis followed by fire testing of thermal protection systems to determine how long they delay thermally induced failure, or if they eliminate failure. In most recent cases the organizations chose to do small scale fire testing because of the obvious cost savings. The question then is – are small scale experiments representative of highway tank truck and rail tank car scales? This paper discusses the scale issues involved. It goes on to show how identical fire heating conditions can give dramatically different failure times and modes of failure for small and large scale tanks if the conditions are not truly similar.

While laser beam profiling techniques are available for the measurement of a laser beam power profile, such techniques are difficult or impossible to use in order to characterize the power profile of the beam which has passed through the light-scattering semi-crystalline polymer (such as nylon). This paper presents a technique for measuring the scattering of the laser beam caused by the laser-transparent part in laser transmission welding. The technique is easy to implement and does not require specialized or expensive equipment. It relies on measurements of line widths for a sequence of lines left on the polymer surface by a rapidly moving laser beam at progressively increasing powers. The line width and power information is then used to obtain the distribution of the laser energy across the weld line. An application for a case of a high-power diode laser and (glass-reinforced and natural) polyamide 6 is presented.

The objective of this work was to determine if the Kachanov one-state variable continuum damage mechanics technique and the MPC omega method could accurately model SA 455 steel’s high-temperature creep behaviour. The steps required for extracting needed material constants from the creep rupture experimental data were presented. Uniaxial finite element analyses were performed using the material constants found for each of the two creep damage techniques. The results of the analyses were carefully compared with the experimental data to show that both CDM and MPC Omega techniques can accurately predict SA 455 steel’s high-temperature creep behaviour. Analyses were performed using commercial finite element analysis computer codes, ABAQUS and ANSYS. It was found that both creep damage techniques were able to accurately predict failure time but that the MPC Omega method was more accurate at predicting creep failure strain.

Experiments have shown that pressure vessels made of ASME SA 455 steel can fail by high-temperature stress rupture in less than 100 min when exposed to accidental fire heat loads. The objective of this work is to develop a three dimensional finite element analysis (FEA) model capable of predicting structural failure in pressure vessels to assess the effects that various parameters have on vessel failure. These parameters included wall thickness, vessel dimensions, wall temperature and vessel internal pressure. Also, the effect of local hot spots on failure time was investigated. The finite element analyses were conducted on 500, 1000 and 33,000 US gallon pressure vessels using ABAQUS. From the results of the three dimensional finite element analyses it was found that shorter and/or thicker walled (with respect to vessel diameter) pressure vessels have greater fire survivability then longer and/or thinner walled pressure vessels. It was also found that if peak wall temperature and internal pressure were the same, pressure vessels exposed to fully engulfing fires would fail sooner than pressure vessels exposed to a local fire impingement. Also, it was shown that the MPC Omega method could be used to predict fast stress ruptures.

For over three decades, products made from expanded aluminum have been available for explosion suppression in fuel tanks and containers. You can find various products on the internet with names like Explosafe, Deto-Stop, Ex-Co or Explo Control, No-Ex, EM2, and others. It appears that Explosafe was the first product to appear in the late 1970s. The expanded aluminum consists of thin aluminum foil that is sliced, stretched and stacked or rolled to produce a highly porous matrix of low-density expanded aluminum. This matrix can be inserted into a fuel tank and it only takes up 1–3% of the tank volume. The matrix has been shown to dramatically reduce overpressures generated by ignition of fuel–air mixtures in a closed space if the closed space is nearly 100% filled with the matrix. The matrix has also been promoted as having other beneficial properties that reduce slosh pressures in dropped fuel tanks, suppression of algae growth, enhanced discharge of static electricity, corrosion protection for steel fuel tanks, and some state it reduces the risk of a BLEVE (boiling liquid expanding vapor explosion) in pressure liquefied gas tanks and pressure vessels. This paper reviews the history of some of these products and presents a summary of the testing that has been performed to prove some of the benefits. It also includes some limited installation experience that shows some of the penalties associated with the products.

The measured blast overpressures from recent tests involving boiling liquid expanding vapour explosions (BLEVE) has been studied. The blast data came from tests where 0.4 and 2 m 3 ASME code propane tanks were exposed to torch and pool fires. In total almost 60 tanks were tested, and of these nearly 20 resulted in catastrophic failures and BLEVEs. Both single and two-step BLEVEs were observed in these tests. This paper presents an analysis of the blast overpressures created by these BLEVEs. In addition, the blast overpressures from a recent full scale fire test of a rail tank car is included in the analysis. The results suggest that the liquid energy content did not contribute to the shock overpressures in the near or far field. The liquid flashing and expansion does produce a local overpressure by dynamic pressure effects but it does not appear to produce a shock wave. The shock overpressures could be estimated from the vapour energy alone for all the tests considered. This was true for liquid temperatures at failure that were below, at and above the atmospheric superheat limit for propane. Data suggests that the two step type BLEVE produces the strongest overpressure. The authors give their ideas for this observation. The results shown here add some limited evidence to support previous researchers claims that the liquid flashing process is too slow to generate a shock. It suggests that liquid temperatures at or above the Tsl do not change this. The expansion of the flashing liquid contributes to other hazards such as projectiles, and close in dynamic pressure effects. Of course BLEVE releases in enclosed spaces such as tunnels or buildings have different hazards.

This paper describes the results from a series of fire tests that were carried out to measure the effect of defects in thermal protection systems on fire engulfed propane pressure vessels. In North America thermal protection is used to protect dangerous goods rail tank-cars from accidental fire impingement. They are designed so that a tank-car will not rupture for 100 min in a defined engulfing fire, or 30 min in a defined torching fire. One common system includes a 13 mm blanket of high-temperature ceramic fibre thermal insulation covered with a 3 mm steel jacket. Recent inspections have shown that some tanks have significant defects in these thermal protection systems. This work was done to establish what levels of defect are acceptable from a safety standpoint. The tests were conducted using 1890 l (500 US gallon) ASME code propane pressure vessels (commonly called tanks in the propane industry). The defects tested covered ∼8% and 15% of the tank surface. The tanks were 25% engulfed in a fire that simulated a hydrocarbon pool fire with an effective blackbody temperature of ∼870 °C. The fire testing showed that even relatively small defects can result in tank rupture if the defect area is engulfed in a severe fire, and the defect area is not wetted by liquid from the inside. A wall failure prediction technique based on uniaxial high-temperature stress rupture test data has been developed and agrees well with the observed failure times.

This paper presents detailed data on the thermal response of two 500 gal ASME code propane tanks that were 25% engulfed in a hydrocarbon fire. These tests were done as part of an overall test programme to study thermal protection systems for propane-filled railway tank-cars. The fire was generated using an array of 25 liquid propane-fuelled burners. This provided a luminous fire that engulfed 25% of the tank surface on one side. The intent of these tests was to model a severe partially engulfing fire situation. The paper presents data on the tank wall and lading temperatures and tank internal pressure. In the first test the wind reduced the fire heating and resulted in a late failure of the tank at 46 min. This tank failed catastrophically with a powerful boiling liquid expanding vapour explosion (BLEVE). In the other test, the fire heating was very severe and steady and this tank failed very quickly in 8 min as a finite rupture with massive two-phase jet release. The reasons for these different outcomes are discussed. The different failures provide a range of realistic outcomes for the subject tank and fire condition.

This paper contains tension and stress-rupture test data on sample railroad tank-car steels at room temperature and temperatures between 500 and 720 °C. The paper describes the test facility, applicable standards, and procedures that were followed during the tests of tension and stress rupture. The paper also contains a simple correlation for the data and gives examples of how it can be used to predict tank failure times when exposed to fire heating. The stress-rupture testing was conducted at constant load (tensile force) conditions. A sample was heated to a specified temperature and the load was applied. The time to failure was then recorded. This testing was needed due to a general lack of available data for the high-temperature stress rupture of tank-car steels. These data are needed for the purposes of predicting tank failure when tank-cars are exposed to heating by fire. The steel samples were obtained from a recent train derailment in Ontario, Canada, and the steel samples included both new and older steels. Samples were cut in both the hoop and longitudinal directions to see if the stress-rupture properties were isotropic. Excellent data were obtained with very little data scatter in each sample. The results show that stress-rupture properties vary from sample to sample. Some older steels were as good as new steels, and some were not. However, all samples were nearly isotropic when it came to high-temperature stress rupture.

Many railway tank-cars carrying hazardous materials are thermally protected from fire impingement by thermal insulation and a steel jacket applied to the outside of the tank-car shell. Over time, it is possible that the thermal insulation will sag, rip, degrade, or be crushed under the steel jacket. A thermographic technique to determine whether or not a tank has insulation deficiencies has been developed, but it is necessary to determine which thermal deficiencies do not affect a tank’s survivability in a fire and which thermal deficiencies must be repaired. In order to develop a guideline in assessing thermal defects, a thermal model and experimental data would be beneficial. A series of fire tests were performed on a quarter-section tank-car mock-up to assist in developing a guideline and to provide validation data for a thermal model. Twelve fire tests, with constant, credible, simulated pool fire conditions, were performed on the tank-car mock-up with various insulation deficiencies. An infrared thermal imaging camera was used to measure the tank wall temperature. The thermal images were useful in determining the temperature profiles across the defects at different times and the transient temperature behaviour at different locations. It was seen that the properly installed thermal protection system significantly reduced the heat transfer from the fire to the tank wall. It was also seen that the steel jacket alone (i.e. 100% defect) acted as a radiation shield and provided a significant level of protection. With small defects, it was observed that the surrounding protected material provided a cooling effect by thermal conduction. A square defect greater than about 40 cm on each side should be considered significant, because unlike smaller defects, there is little benefit from the surrounding material as far as the peak defect temperature is concerned.

A novel FET concept, using low temperature grown GaAs as surface passivation and buffer layer material, has been developed to tolerate high levels of input overdrive and to improve electrostatic discharge (ESD) resistance. It is shown that high input levels 17 dB beyond the 1 dB compression point, do not lead to the burnout of the device and that, at the same time, the ESD failure voltage can be increased compared to conventional GaAs based MESFETs.

The impact of several buffer concepts on the resulting MODFET behaviour has been investigated. Best DC and RF results are found for thick linear graded Si60Ge40 buffers from which enhancement and depletion mode MODFETs were simultaneously fabricated in one chip using a differently deep-gate recess. The layer sequence grown on a 2 μm thick linear graded buffer consists of a strained Si two-dimensional electron gas channel and for the first time of highly Ge containing layers (Si0.55Ge0.45). High Hall mobilities (μ=1190 cm 2 / V s ) and elevated sheet carrier densities (n s =4.4×10 12 cm −2 ) are achieved at room temperature. Applying a 0.15 μm e-beam T-gate (gate-source spacing 0.2 μm ) yields reduced parasitic resistances (R G =250 Ω mm −1 , R S =0.18 Ω mm ) and high saturation currents up to 320 mA/mm. Depletion HFETs show room temperature and 77 K transconductances of g me ( RT )=286 mS / mm and g me (77 K )=411 mS / mm , respectively, cut-off frequencies ft up to 43 GHz and fmax up to 92 GHz – the highest fmax reported so far for SiGe MODFETs. Enhancement HFETs with g me ( RT )=476 mS / mm or g me (77 K )=784 mS / mm and ft up to 30 GHz and fmax up to 52 GHz have been realized.

Recent fire tests involving over forty, 4001 automotive fuel tanks filled with commercial propane have shown that the likelihood of a BLEVE and the severity of its hazards are significantly affected by the detailed thermodynamic condition of the lading at the time of failure. When the liquid in a tank is heated by fire impingement on the tank external shell, the liquid near the heated wall will tend to rise because of buoyancy effects. This leads to the development of temperature stratification where the liquid near the top of the tank will be at a higher temperature than liquid lower down. The pressure in the tank is dictated by the warmest liquid. This means that when the liquid is stratified the pressure in the tank is higher than the pressure one would calculate from the average liquid temperature. If the tank fails at the pressure relief valve (PRV) set pressure the resulting release will be less powerful if the liquid is stratified. When the PRV is activated on a tank it usually vents vapour to the surroundings. This vapor flow results in boiling action in the liquid and this boiling causes heat transfer and mixing and these cause destratification of the liquid. The time for destratification increases with the scale of the system. Eventually, the PRV may eliminate the stratification and the liquid will consist of a near isothermal liquid mass. If the tank fails when it is full of liquid, and the liquid is uniformly at the saturation temperature for the PRV set pressure, then the resulting BLEVE and hazards will be maximized for the given tank. Based on recent fire test data, this paper discusses how temperature stratification and destratification is affected by the fire type and the PRV action. The paper also discusses how this temperature stratification effects the likelihood of a BLEVE, and the severity of the associated hazards including fireball heat flux, blast overpressure and projectiles.

Recent fire tests of 400-litre automotive propane tanks has provided some new data on hazards from boiling liquid expanding vapour explosions (BLEVEs). Of the 40 fire tests conducted, 13 resulted in BLEVEs. The hazards from these included fireballs, projectiles and blast. This paper presents a simple analysis of the projectile hazards and compares the results with other projectile data from fire tests and accidents ending with BLEVEs. Then, the projectile hazards are compared with existing correlations for the hazards from blast and fireballs. Finally, a proposal is presented for working distances as a function of tank scale, for emergency responders dealing with potential propane or LPG BLEVEs. Projectile, blast and fireball hazard distances have been normalized in terms of a single distance unit — fireball radii. When presented in this way the hazards from a BLEVE can be summarized together, for various tank scales, in a simple and logical way. The proposal applies to accidents where a propane or LPG tank has suffered a significant loss of strength and therefore a BLEVE is possible. The loss of strength may be due to impact damage, or severe fire exposure. In this situation it is proposed that emergency responders should set up an observation position upwind and to the side (not the ends) of a damaged tank, at a position no closer than four fireball radii, to a minimum of 90 m. In this case the fireball radii has been calculated from the expression R = 3 m0.33, where m is the propane mass in kg, and R is the fireball radii in metres. At this position the responders will be reasonably safe from fireball, blast and projectile effects. At 4R, the radiant heat flux should be less than 21 k W m−2, the blast should be less than 30 mbar, and most (80–90%) projectiles should fall short of this distance. However, some projectiles can and will go further than four fireball radii and therefore responders are urged to stay further back if possible. The public should be evacuated to a minimum distance of 15 fireball radii, 30 if possible.

When a tank carrying a pressure-liquefied gas (PLG) is exposed to fire impingement, there is a risk of thermal-induced rupture of the tank. If the tank ruptures, the potential hazards include blast, projectiles, fire and toxic exposure. These hazards are associated with all possible scales of PLG containers from small handheld lighters to huge storage spheres. Over the years, many researchers have conducted scale fire-testing of tanks to improve understanding of the failure process and the associated hazards. These tests have been done at various scales from glass tubes and spheres containing a few cubic cm to full-scale rail tank cars carrying 130000 litres or more. These tests have been used to improve models for fireball diameters, duration, and blast and projectile effects. They also highlight very interesting features of the heating process and the failure mechanisms. One of the most strongly debated scale issues relates to the flash evaporation of pressure-liquefied gases upon sudden depressurization. If the conditions are right, a tank failure may lead to sudden depressurization of the PLG and this may trigger an explosive phase change resulting in a boiling liquid-expanding vapour explosion (BLEVE). This topic has been an active area of research for many years. The objective of this paper is to provide an overview of scale issues as they relate to the heat-up and failure of a PLG container. It is hoped that this material will be useful for emergency responders, so they can understand better the issues of scale when dealing with accident situations.

When a rail or highway tanker carrying a hazardous commodity is involved in an accident it is sometimes difficult to move the tank or empty the contents. For example, if the tank structure is such that the tank cannot be moved and the existing valving is damaged or inaccessible, it is not a simple matter to offload the contents of the tank. In these situations it may be necessary to tap into the tank so that the contents can be pumped out. Once the tank is emptied it can then be moved safely. The tapping process requires that a tapping flange be attached to the tank wall. In many industrial applications this flange is welded or chained to the pipe or pressure vessel. In this application welding is not possible because of the potential hazards and the use of chains may be limited by accessibility. One possibility is to use steel on steel adhesives and/or magnets for attaching the tapping flange. The feasibility of using adhesives and magnets is reviewed in terms of existing tapping technology, an analysis of the tapping environment, and an industry survey of adhesives and magnets. From this study it appears that both adhesives and magnets are suitable for affixing a tapping flange to a tank-car and recommendations are made on a program for developing tapping equipment and associated procedures.

The boiling liquid expanding vapour explosion (BLEVE) has existed for a long time and for most of this time it has been cloaked in mystery. Several theories have been put forward to explain this very energetic event but none have been proven. This paper describes a series of tests that have recently been conducted to study this phenomenon. The study involved ASME code automotive propane tanks with nominal capacities of 400 litres. The tanks were exposed to a combination of pool and/or torch fires. These fire conditions led to thermal ruptures, and in some cases these ruptures resulted in BLEVEs. The variables in the tests were the pressure-relief valve setting, the tank wall thickness, and the fire condition. In total, 30 tests have been conducted, of which 22 resulted in thermal ruptures. Of those tanks that ruptured, 11 resulted in what we call BLEVEs. In this paper, we have defined a BLEVE as the explosive release of expanding vapour and boiling liquid following a catastrophic tank failure. Non-BLEVEs involved tanks that ruptured but which only resulted in a prolonged jet release. The objective of this study was to investigate why certain tank ruptures lead to a BLEVE rather than a more benign jet-type release. Data are presented to show how wall temperature, wall thickness, liquid temperature and fill level contribute to the BLEVE process.

Effects of intensive cultural treatments on above-ground biomass production and nutrient distribution were examined in flooded gum (Eucalyptus grandis) plantations established in their native habitat near Coffs Harbour, N.S.W., Australia. Flooded gum biomass in the most intensive treatment combination of NPK fertilizers plus weed control and insecticides applied for 6 years was 274 tonnes ha−1 after 9.25 years, more than double the control stand biomass of 133 tonnes ha−1. A further 15 to 20 tonnes ha−1 accumulated as forest floor organic matter, and 6 tonnes ha−1 as understorey shrubs. Acacias developed into small trees in all plots except those treated intensively with weedicides. Maximum nitrogen, phosphorus, and calcium accumulations occurred in the most intensively treated stands (549 kg N ha−1, 50.7 kg P ha−1 and 1118 kg Ca ha−1) and were 2 to 3 times higher than those found in the controls. Fertilizers increased phosphorus concentrations in foliage and branches, and calcium in branches, and decreased nitrogen concentrations in heartwood. The proportions of total biomass and nutrients in various tree components were not altered substantially by the cultural treatments. A thinning treatment was carried out at 9.75 years and E. grandis plus Acacia biomass were determined at 12 years of age. Both responded to the thinning treatment, nut there was no further response to the initial fertilizer applications. There was no difference between the biomass of flooded gum in the most intensive treatment and the biomass of flooded gum plus Acacia in all other treatments. Phosphorus contents were also equal regardless of treatment but the nitrogen content of stands with Acacia exceeded the nitrogen content of flooded gum alone. Biomass and nutrient contents of flooded gum and other Eucalyptus plantations were compared with similar data for native eucalypt forests. Native forests have relatively low nutrient contents, whereas plantations exhibit an almost linear increase in nutrient content with increasing biomass. Phosphorus and calcium contents of plantations are higher than those of native forests at equivalent levels of above-ground tree biomass.

DERACS (Derailment Accident Computer Simulation) is a computer program developed to simulate some of the consequences of train derailment accidents involving fires and accidental releases of dangerous commodities. The present paper shows the results of two sample simulations that were performed using the prototype DERACS program. Technical details of the DERACS program are presented in Reference [1]. Because of the limitations of the prototype version of DERACS the sample simulations only approximate the Mississauga rail accident of November 1979. The results presented have not been validated in any way and should not be considered as accurate representations of the Mississauga accident. They were generated for discussion purposes only so that future applications of the DERACS program could be illustrated, and areas within DERACS requiring further development could be identified.

A prototype computer program has been developed which is capable of simulating some of the consequences of a train derailment accident. The program is made up from a number of models which account for train derailment mechanics, flammable liquid spills, fire effects on remote targets, fire impingement on tank cars carrying dangerous commodities, explosion blast over-pressure and thermal radiation, and heavy plume and puff dispersion. Most of these sub-models have previously been developed and are available in the open literature. The overall program consists of a pre-processor for inputting the surroundings data and train consist data, a simulation module containing the various models and a post-processor which presents the results of the simulation in graphical form. The present paper briefly describes the overall organization of the program and the technical basis of the simulation models.

In a client-centered case management model, the case manager's personal relationships with the client and caregiver help the case manager to effectively assess the client's needs, coordinate needed care, and monitor services provided. At Connecticut Community Care, Inc (CCCI), case management is a six-step process that includes referral, assessment, care planning, service coordination, monitoring, and documentation. The program is particularly notable for its use of a structured, comprehensive assessment tool and a case management team consisting of a nurse and a social service professional.

In this paper two studies are described which examine racial and sex role stereotyping in career information illustrations. In Study 1 over 2000 illustrations, from sources including the Occupational Outlook Handbook (OOH) and The Encyclopedia of Careers , were analyzed according to seven dimensions. In Study 2 a follow-up analysis was done comparing illustrations in the original OOH with a revised edition. Findings are discussed from the perspective of practical implications for vocational counselors.

Patterns of fine-fuel reduction and accumulation following repeated prescribed burns between 1967 and 1986 in blackbutt (Eucalyptus pilularis Sm.) forests of the Manning River National Forest were examined and compared with the effect of an unscheduled or ‘wild’ fire. Prescribed burning at 2 and 4-year intervals reduced available fine-fuels by an average of 59% with no apparent long-term effect on fuel composition or litterfall inputs. Mean annual litterfall was 7.28 t ha−1 and 7.45 t ha−1 on the control and 2-year burn plots, respectively. Rates of fine-fuel accumulation were very rapid, and within 2 years the fine-fuel mass was equivalent to about 75% of the fine fuel load carried by the control stands. Four years after fire there was no difference between the fuel levels in control and burned stands (20 t ha−1). With repeated burning, however, particularly at 2-year intervals, the understorey of woody shrubs was replaced by a layer of grasses. In the absence of fire, fine-fuel turnover was relatively high to the extent that only 2.4 years of litter input accumulated as available fine fuel. Wildfire reduced fine-fuels by 90–100%, altered fuel composition, litterfall inputs and patterns of fuel accumulation. After 6 years the fine-fuel mass was only 73% of the pre-wildfire levels and contained more understorey vegetation, including shrubs and grasses. Regular fuel-reduction burning may increase the probability of controlling chance outbreaks of fire in blackbutt forests, but fine-fuel levels 2–4 years after fire would be capable of carrying a high-intensity fire. In terms of forest management, the results suggest that it is important to develop prescribed-burning guidelines for specific forest types and regions.

a multi-detector high efficiency spectrometer for the detection of electron-positron pairs in the presence of high intensity gamma radiation has been designed, built and tested. The spectrometer employs six RCA 8850 photomultipliers. A “sandwich” made of a 0.5 mm thick anthracene glued to the front face of a 45 mm thick NE 102A plastic scintillator was mounted on each photomultiplier. A pulse shape discrimination circuit distinguishes electron from gamma signals, making use of the fact that electrons produce a relatively long scintillation pulse (≈ 25 nrmns) in the anthracene, whereas gammas have a negligible probability to interact with the thin anthracene. The six scintillators cover a solid angle of 3.2 π sr around the target and their front surfaces form nine boundary lines. An annular Si(Li) detector (0.081 sr) used to detect particles backscattering from the target may be operated in coincidence with the electron detector. Proper adjustment of the pulse shape discriminators resulted in accepting the electrons from a 207Bi source and in rejecting 98% of 60Co radiation. The spectrometer was tested using the reaction 19F(p, α)16O at 2.47 MeV proton bombarding energy. Approximately 90% of the 7.12 MeV gammas from the 1− level in 16O were rejected. The pairs from the 6.05 MeV O+ level were detected with 28% efficiency and 12% energy resolution (fwhm).

A computer model has been developed which can simulate the response of a tanker and its lading to external fire impingement. The model was developed as a tool to study the effectiveness of new concepts in thermal protection of tankers. The computer model can simulate a long cylindrical tank filled partially with liquid and partially with vapour exposed to either an engulfing type fire, such as caused by a burning pool, or a torch type fire, such as that caused by a relief valve flare from a neighbouring tank. The model can account for the effects of a number of thermal protection devices such as pressure relief valves, thermal insulation, radiation shielding, temperature sensing relief valves, and novel internal protection devices, including heat dissipating matrices. The model can simulate the effects of roll and pitch of the tank. The computer model is capable of predicting the tank internal pressure, mean lading temperatures, wall temperature distribution, relief valve flow rates, liquid level, tank wall stresses and tank failure all as functions of time from initiation of the fire impingement. The model has been validated by comparing its predictions with the results of numerous fire tests involving full and fifth-scale rail tank-cars exposed to engulfing fires. Several examples of these validation runs are presented and discussed.

A chopper-buncher system for heavy ions has been designed, constructed and put into operation. The system was incorporated into a 14UD Pelletron electrostatic accelerator and produced beam pulses of 240 ps fwhm for 16O ions at the target. The chopper buncher is suitable for bunching 1H through 4He as well as all ions from 12C to 58Ni. The beam is chopped by a novel deflector-redeflector chopper, which, in first order, does not increase the beam energy spread. The low energy buncher operates at 3.36 MHz basic frequency and 10.08 MHz harmonic correction and bunches the beam to under 1 ns fwhm. For higher time resolution, a 215 MHz copper cavity buncher is used. This buncher is located at the high energy side of the Pelletron before the switching magnet and it provides bunches of under 300 ps fwhm to all beam lines. An additional high energy buncher consisting of a superconducting 430 MHz niobium cavity is located on one particular beam line. This buncher, which is only 3 m distant from the target, can produce bunches of less than 100 ps fwhm when injected with bunches under 500 ps fwhm. Each of the system elements is amplitude locked and the low energy chopper-buncher elements are phase locked to the high energy buncher used. A microchannel plate timing detector is used for feedback correction of the low energy chopper-buncher phase, maintaining the proper arrival time of the beam bunches at the high energy buncher or at the target.

A system employing four semiconductor detectors and four NaI(Tl) scintillation counters for particle-gamma angular-correlation measurements at high counting rates is described. Scintillation counter pulses are shaped into rectangular pulses of 200 ns duration in order to reduce pile-up effects, and a compensation circuit for gain variation with rate is used. A fast decision-making logic unit employing MECL 10000 I.C.'s controls data transfer into an on-line PDP-9 computer. Dead-time losses are measured using a pulse-pair generator simulating particle-gamma coincident pulses. In an experiment with 5–8 MeV protons and 0.5–2.5 MeV gamma rays at a counting rate of approximately 100 000 cps at each of the scintillation counters, the gamma-energy resolution (fwhm) was 6–9%, depending on gamma energy, and the time resolution (fwhm) was 1.8 ns. Plots of typical results are shown.

A computer model has been developed which is capable of simulating the effects of torch fire impingement on a long cylindrical tank filled partially with liquid and partially with vapour. The model was developed to study the effects of fire impingement on rail and highway tankers carrying hazardous commodities. The model is capable of predicting the transient thermal and structural response of the tank when exposed to the torch fire impingement, including tank pressure, wall and lading temperatures, relief valve flow rates, liquid level and wall stresses and strength. Simulation results for uninsulated tanks show that severe torch fire impingement can result in a tank thermal rupture within a few minutes after torch application, if the torch is applied where the tank wall inner surface is in contact with vapour. The simulations also show that as long as liquid wets the wall in the area of the torch application, and as long as the fluid critical heat flux is not exceeded, thermal rupture is unlikely. However, when the liquid level drops below the area of torch application, as may be the case if the relief valve is operating, the tank is likely to fail within a few minutes if the torch impingement continues. Validation results are presented for the case of an empty full-scale uninsulated tank exposed to a torch fire, and an uninsulated full-scale tank filled partially with propane exposed to an engulfing fire. Simulation results are presented for uninsulated tank-cars filled partially with propane exposed to torch fires applied at different locations around the circumference of the tank. Comparisons are made between the cases involving torch fires and the validation case involving the engulfing fire.

The computer control system and the electronics hardware of the superconducting booster module recently installed at the Weizmann Institute of Science Pelletron accelerator laboratory are described. The resonators' rf controllers and the control system software are described in detail.

Toxin was obtained from the cyanobacterium Microcystis aeruginosa PCC 7941 by extracting freeze-dried cells with water-saturated, acidified n-butanol, diethyl ether—water distribution, reversed-phase thin-layer chromatography and silica high-performance liquid chromatography (HPLC). Two toxic peptide fractions resulted from HPLC. One of these fractions was analyzed by UV and NMR spectroscopy. amino acid analysis and fast atom bombardment mass spectroscopy. The following amino acids were identified: β-methyl-Asp, Thr, Glu, Ala, Val, Leu, Phe, Arg, N-methyldehydro-Ala and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid. Yet the mass spectroscopic data showed that the fraction was still composed of several, most likely cyclic peptides that did not stain with ninhydrin.

A polyethylene proton radiator placed in front of a solid state detector was used for fast neutron spectroscopy. Protons scattered at small forward angles were detected, giving a resolution of 270 keV for neutrons of 6 MeV. The possibility of using internal (n, p) and (n, α) reactions in the silicon of the detector for fast neutron spectroscopy has been investigated. A resolution comparable with that observed for direct detection of charged particles was obtained. For neutrons in the region of 6 MeV, the cross-sections were found to be of the order of 50 millibarns. The construction of a detector made of Si29 separated isotope is suggested. The reaction Si29(n, α)Mg26 resonates at En=5.35 MeV, indicating a level of 15.96 MeV in Si30/

The reaction 19 F(p, α) 16 O ∗ was used to populate levels in 16 O. Delayed coincidence measurements of α-π and α-γ gave a value of 96±7 ps for the mean life of the 6.05 MeV 0 + level in 16 O.

A comparative study of the Li6(d, p)Li7 and Li6(d, n)Be7 reactions has been made in order to serve as a critical test of the principle of charge symmetry in nuclear reactions. The ground and first excited states of Li7 and Be7 are believed to be pure isobaric spin doublets. The need has been eliminated for substantial Coulomb and phase space corrections, since the ratios of the ground to first excited state cross-sections are compared. The observed equality of the neutron and proton results over the bombarding energy range 0.4-3.2 MeV may be taken as a striking and model independent confirmation of the principle of charge symmetry. An interesting anomaly in the angular distribution results was observed which does not seem explainable in ordinary distorted wave stripping theory.

An instrument employing closed-circuit television for the measurement of coordinates and bubble density of charged particle tracks in bubble chamber photographs is described. The instrument uses a Moire fringe image plane digitizer. With the aid of servo-motors, a vidicon camera can be moved in the X and Y directions and can also be rotated. Once set on the proper track by the operator, the vidicon follows the track in a staggered motion. At each stop, the machine automatically punches out onto IBM cards the X and Y coordinates of the center of the track and also the total length of the gaps and the number of gaps in the segment. The least count in the image plane is 10 μm. Ionization measurement reproducibility checks gave a standard deviation of ±3%. In an actual experiment, the rms deviation of the measured ionization from that calculated from the kinematics was less than ±14%, and the measuring rate was 4 events/h.

An interface between a programmable desk calculator and a multichannel pulse height analyzer is described. Peak integration with background subtraction is performed on-line, approximating the background curve by a straight line defined by two manually adjustable points which appear intensified on the screen of the analyzer.

Compensation for gain increase with rate in a NaI(Tl) scintillation counter was achieved by using dc negative feedback from the collector of the photomultiplier tube to its dynodes' resistor chain. A 16% gain variation was reduced to 1% by using a nonlinear collector load consisting of resistors paralleled by Zener diodes.