Search

MBX is a C++ library that implements many-body potential energy functions (PEFs) within the “many-body energy” (MB-nrg) formalism. MB-nrg PEFs integrate an underlying polarizable model with explicit machine-learned representations of many-body interactions to achieve chemical accuracy from the gas to the condensed phases. MBX can be employed either as a stand-alone package or as an energy/force engine that can be integrated with generic software for molecular dynamics and Monte Carlo simulations. MBX is parallelized internally using OpenMP, and can utilize MPI when available in interfaced molecular simulation software. MBX enables classical and quantum molecular simulations with MB-nrg PEFs, as well as hybrid simulations that combine conventional force fields and MB-nrg PEFs, for diverse systems ranging from small gas-phase clusters to aqueous solutions and molecular fluids to biomolecular systems and metal- organic frameworks.

Glass provides many opportunities for advanced packaging. The most obvious advantage is given by the material properties. As an insulator, glass has low electrical loss, particularly at high frequencies. The relatively high stiffness and ability to adjust the coefficient of thermal expansion gives advantages to manage warp in glass core substrates and bonded stacks for both through glass vias (TGV) and carrier applications. Glass also gives advantages for developing cost effective solutions. Glass forming processes allow the potential to form both in panel format as well as at thicknesses as low as 100 um, giving opportunities to optimize or eliminate current manufacturing methods. As the industry adopts glass solutions, significant advancements have been made in downstream processes such as glass handling and via/surface metallization. Of particular interest is the ability to leverage tool sets and processes for panel fabrication to enable cost structures desired by the industry. By utilizing the stiffness and adjustable CTE of glass substrates, as well as continuously reducing via size that can be made in a panel format, opportunities to manufacture glass TGV substrates in a panel format increase. We will provide an update on advancements in these areas as well as handling techniques to achieve desired process flows. We will also provide the latest demonstrations of electrical, thermal and mechanical reliability.

To examine the incidence and risk factors of firework-related injuries during the Last Wednesday Eve Festival in Tehran, Iran, with a focus on the association of socio-economic status and educational level with the use of fireworks and the incidence of firework-related injury.Cross-sectional household survey.Using a random cluster sampling approach, a household survey was conducted in Greater Tehran in April 2008. During a structured interview with an adult member of the household, questions were asked about the use of fireworks and any firework-related injuries sustained by household members during the preceding festival. Data were gathered on expenditure on fireworks, medical treatment of firework-related injuries, length of hospital stay for the treatment of these injuries, and damage to personal property by fireworks.The survey included 2456 households in Greater Tehran. At least one member of 18% of these households had used fireworks during the Last Wednesday Eve Festival in 2008. The overall incidence of firework-related injuries was 100 per 100,000 population (95% confidence interval 37-163). The use of fireworks was less common among parents and more common among male children. Individuals who used fireworks were younger than non-users. Younger age and use of fireworks were associated with firework-related injuries (P 0.05). The mean household expenditure on fireworks was US$1.62. Among the households that had bought fireworks, the mean expenditure was US$9.40 (standard deviation US$16.34). Thirty-two households (1.3%) reported damage to personal property due to fireworks during the festival costing US$3.30-167.20. The regional price of housing in the study area was correlated with the educational level of the head of the household. Higher educational level of the head of the household was associated with participation in firework activities by household members, expenditure on fireworks, and the amount of financial loss due to fireworks (all P 0.05).Fireworks are associated with serious injuries, and impose a non-trivial financial burden on families. While personal use of fireworks was an independent risk factor for firework-related injuries, higher socio-economic status of the household and higher educational level of the head of the household were not protective factors.

This paper reports on a study into the aggregate power quality from multiple grid connected inverters. Measurements are presented for individual single-phase inverters generating into the low voltage network under a range of operational conditions, and for groups of similar converters connected at the same point on the network. Some results from the modeling of multiple inverter interaction are also presented. Particular attention is given to power factor, the harmonic content of the generated currents, and dc injection.

Background: Double contrast barium enema (DCBE) is the examination carried out most frequently for investigation of patients with large bowel symptoms. The aim of this study was to compare the sensitivity of DCBE and colonoscopy for the detection of colorectal cancer and neoplastic polyps ?1 cm. Methods: All patients undergoing DCBE (1389) or colonoscopy (1081) as the primary investigation for large bowel symptoms or for cancer or polyp surveillance in the first 9 months of 1997 at a large teaching hospital were included in this study. At 1 and 2 years following investigation, a computerized search of appropriate diagnosis and procedure codes to detect any missed cancers or polyps was performed for all patients with a normal investigation. Results: Almost 19% of patients in both groups went on to have an additional large bowel investigation over the 2-year period. In the DCBE group, 47 patients (3.5%) had a cancer diagnosed; eight of them had been missed at the primary investigation (sensitivity 83%). In the colonoscopy group, 37 patients (3.4%) had a cancer; one of them had been missed at the primary investigation (sensitivity 97.5%). Neoplastic polyps ?1 cm were diagnosed in 1.6% of the DCBE group and in 7.7% of the colonoscopy group, with sensitivities of 21.7% and 91.4%, respectively. Nine patients (0.6%) had a false positive diagnosis of cancer in the DCBE group; one had an iatrogenic bowel perforation following flexible sigmoidoscopy. Conclusions: Where adequate facilities and expertise exist, colonoscopy should be the investigation of choice for most patients with large bowel symptoms suggestive of neoplastic disease.

The power density of converters and drives can benefit from higher operating frequencies, and adaptive control methods can increase system response and stability. The functionality of the finite state machine provides an ideal platform to build a high-frequency adaptive controller for power electronics applications. This article describes the essential features of a finite state machine, the analysis and design basics, and how the adaptive control methods are used to increase the performance. To conclude, the design, simulation and implementation of an FSM controller for a 1.5 kW 25 kHz power converter is presented.

Positive advantages result from the variable speed operation of wind turbines connected to a power utility. Conventionaly thyristor based power interfaces have been used to achieve this and more recently IGBT based converters have shown advantages of improved power quality to the network. This paper describes a novel IGBT converter designed built and tested through collaborative research on the European Commission JOULE programme on Renewable Energy.

An HPLC method was developed and validated for the determination of ceftiofur-related metabolites that have the potential to be microbiologically active in swine muscle, kidney, liver and fat. Its performance was evaluated against incurred-residue swine tissues. This method is based on the cleavage of the disulfide and/or thioester bonds between the metabolites and their conjugate sulfur containing moiety using dithioerythritol to yield desfuroylceftiofur, and further stabilization to desfuroylceftiofur acetamide. The limit of quantitation was 0.1 micrograms ceftiofur equivalents/g tissue. The assay is specific for ceftiofur-related metabolites when evaluated against commercially available antibiotics for swine.

We have magnetically driven a tapered-thickness spherical aluminum shell implosion with a 12.5 MA axial discharge. The initially 4 cm radius, 0.1 to 0.2 cm thick, [plus minus]45[sup [degree]] latitude shell was imploded along conical electrodes. The implosion time was approximately 15 [mu]sec. Radiography indicated substantial agreement with 2D-MHD calculations. Such [ital calculations] for this experiment [ital predict] final inner-surface implosion velocity of 2.5 to 3 cm/[mu]sec, peak pressure of 56 Mbar, and peak density of 16.8 g/cm[sup 3] ([gt]6 times solid density). The principal experimental result is a demonstration of the feasibility of electromagnetic-driven spherical liner implosions in the cm/[mu]sec regime.

This study was designed to investigate and identify factors relevant to the success and failure of posterior resin-bonded bridges (PRBBs) related to the patient, technique, operator and bridge design. It was a long-term controlled clinical trial and formed part of a multicentered study on PRBBs. Data are presented 2.5 years from the start of the study. Following a strict protocol for case selection, 54 posterior, resin-bonded, fixed-fixed, three unit bridges were placed in 45 patients. Twenty-four patients with 27 PRBBs attended for 2.5-year recall. Treatment variables were limited to one of two operators and either a conventional tooth preparation or a more extensive modified preparation was performed. The allocation of treatment modalities was performed using a computer program to balance patient variables such as age, gender, location of bridge, restoration of abutment teeth. All bridges were produced in one laboratory, treated to produce a silicate-coating bond and placed using Microfill Pontic C (Kulzer, Wehrheim, Germany). Data relating to the patients, the open spaces, bridge preparation, bridge placement and subsequent annual evaluation were recorded. The survival of PRBBs in the maxilla was 77% and in the mandible 47%.

Six design options for a scintillating fiber inner tracker for the SDC detector operating at the Superconducting Super Collider (SSC) are simulated. Concentric cylindrical configurations of axial fiber superlayers, ranging from four to six in number, are considered. Tracks from events generated by Pythia 4.8 at rates up to ten times design luminosity are swum through the tracker. Algorithms for reconstructing tracks of physics interest with p T > 10 GeV/ c among a background of low p T tracks are described. The optimum configuration found permits level 1 triggering up to η = 2.3 at ten times design luminosity. Inclusion of additional stereo fibers in this configuration permits level 2 stereo reconstruction up to eight times design luminosity.

Third instar larvae of the sugarbeet root maggot ( Tetanops myopaeformis von Roder) were challenged with three strains of Steinernema carpocapsae (Weiser), two strains of S. feltiae (Filipjev), and one strain of S. glaseri (Steiner). Steinernema carpocapsae "SCANMASK" (1.3%) showed the lowest level of infectivity, followed in ascending order by S. carpocapsae "ALL" (2.8%), S. carpocapsae "252" (4.4%), S. glaseni "326" (5.5%), S. feltiae "SN" (6.4%), and S. feltiae "UK" (8.6%). In several of the nematode challenges of diapaused larvae, resulting pupae gave rise to adult flies with gross abnormalities. Microscopic examination of these pupae gave no indication of nematode infection or an ensuing septicemia. Overall, 24.4% of the imagos arising from nematode-challenged larvae gave rise to aberrant adults. We have attributed these aberrant adults to an accelerated metamorphosis. These aberrant flies did not produce eggs, although mating attempts were observed.

Trackers based on scintillating-fiber technology are being considered by the Solenoidal Detector Collaboration at SSC and the DO collaboration at Fermilab. Some 600 fibers in the Fermilab Tevatron CO area were irradiated, thereby obtaining a hadronic irradiation at realistic rates. Four-meter-long samples of ten Bicron polystyrene-based fibre types, maintained in air, dry nitrogen, argon, and vacuum atmospheres within stainless-steel tubes, were irradiated for seven weeks at various distances from the accelerator beam pipes. Maximum doses, measured by thermoluminescence detectors, were about 80 krad. Fiber properties, particularly light yield and attenuation length, were measured over a one-year period. A description of the work together with the results is presented. At the doses achieved, corresponding to a few years of actual fiber-tracking detector operation, little degradation was observed. Recovery after several days' exposure to air was noted. Properties of unirradiated samples kept in darkness show no changes after one year. >

The objective of this study was to determine factors that could effect maximum sugar yield of sweet sorghum (Sorgum bicolor (L.) Moench) at temperature zone locations. Four sweet sorghum cultivars were tested for fermentable sugar production potential under irrigated and non-irrigated conditions with 0, 84, and 186 kg ha−1 of added nitrogen fertilizer at two temperature zone locations (40·8° and 42°N latitude). Test sites represented a typical temperate zone irrigated location and a typical corn belt natural rainfall area. Average ethanol (EtOH) yields for the 2-year study were above 3100 liters ha−1 and ranged up to 5235 liters ha−1. The irrigated location produced more gross green weight (89·9 Mg ha−1) compared with the natural rainfall location (65·0 Mg ha−1), but total sugar yield and theoretical EtOH were not significantly different. The results emphasize the potential of sweet sorghum as an alternative energy crop, capable of insulating ethanol prices from shifts in corn prices. Added nitrogen fertilizer had little discernible effect on increasing fermentable sugar production.

Ion channeling and Auger electron spectroscopy were used to investigate the initial growth of cobalt and nickel disilicide on boron stabilized Si(111)√3 × √3-B surfaces at room temperature. The results show that Co and Ni interact initially at subsurface sites and then the reaction proceeds toward the surface forming a barrier to further interaction.

A test facility to study the light-transmission properties of scintillating fiber waveguides for tracking applications in high-energy physics is being developed. A light-tight box 2 m in length has been built, and data acquisition hardware and software is in place for testing various aspects of scintillating fibers and waveguides. Scintillating fibers have been excited with radioactive sources, ultraviolet light sources, and light-emitting diodes. Various photodetectors such as photomultiplier tubes, photodiodes, charge-coupled devices and solid-state photomultipliers have been utilized to detect the transmitted light. Studies of attenuation length and transmission through splices are presented. >

The five-year findings of a study to compare the performance of restorations of Occlusin (ICI Dental, Macclesfield, UK) in butt-joint and bevel-edged preparations are reported. Ninety-four (79%) of the restorations originally placed were reviewed at five years, 20 restorations (17%) having failed during the study. Initial analysis of the overall results having failed to reveal any significant differences between the five-year performance of the two types of restorations, the results were combined and analyzed by Chi-square tests and step-wise logistic regression. Chi-square analysis indicated that of the independent variables investigated, size of restoration had the greatest effect on clinical performance. Step-wise logistic regression revealed that only four of the eight dependent variables investigated showed significant predictive relationships with the independent variables, the logistic equation for occlusal marginal adaptation being the most complex. The greatest amount of generalized occlusal surface wear tended to be seen in large-sized Class II restorations in molar teeth, with the main factor influencing wear being found to be the type of restoration (Class I or Class II). It is concluded that the performance of restorations of Occlusin has not been found to differ significantly in butt-joint and bevel-edged preparations after five years in clinical service. Step-wise logistic regression has been found to be a useful tool in the analysis of data obtained during the clinical evaluation of a restorative material.

The defect density of 2500 A thick Ag films grown on Si(111) and Si(100) substrates by molecular beam epitaxy have been studied using MeV ion channeling and Rutherford backscattering spectrometry (RBS). Ion channeling measurements indicate that despite the large lattice mismatch between Ag and Si (~ 25%), the Ag films showed excellent epitaxy (χ min = 6–20%). In the best cases, the minimum yield was close to that expected for a perfect Ag crystal. Dechanneling was observed due to defects, predominantly dislocations which were distributed throughout the Ag film. Near the Ag/Si interface, the dislocation density was an order of magnitude higher than that found for the bulk of the Ag(111) film and produced an interface peak in the channeling spectra. These results show that high quality epitaxy can be achieved for even large mismatched heteroepitaxial systems such as Ag on Si and illustrate the power of the ion channeling technique for studying defects in crystalline films.

[1] The Dionysius region is located near the western edge of Mare Tranquillitatis and is centered on Dionysius crater, which exhibits a well-developed dark ray system. Proposed origins for these dark rays included impact melt deposits and dark primary ejecta. The region also contains extensive deposits of Cayley-type light plains. Clementine multispectral images and a variety of spacecraft photography were utilized to investigate the composition and origin of geologic units in the Dionysius region. The portions of the dark rays for which spectral and chemical data were obtained are composed of mare debris contaminated with minor amounts of highland material. Both five-point spectra and values of the optical maturity (OMAT) parameter indicate that the dark rays are dominated by mare basalts, not glassy impact melts. The high-albedo rays associated with Dionysius exhibit FeO and TiO2 values that are lower than those of the adjacent dark ray surfaces and OMAT values that indicate that bright ray surfaces are not fully mature. The high-albedo rays are bright largely because of the contrast in albedo between ray material containing highlands-rich ejecta and the adjacent mare-rich surfaces. The mafic debris ejected by Dionysius was derived from a dark, iron-rich unit exposed high on the inner wall of the crater. This layer probably represents a mare deposit that was present at the surface of the preimpact target site. With one possible exception, there is no evidence for buried mare basalts associated with Cayley plains in the region.

Summary form only given, as follows. Quasispherical solid liner implosions with little or no instability growth have been achieved experimentally. Applications for such implosions include the uniform, shock-free compression of some sort of on-axis target. One proposed means of obtaining such compression is to inject a 1 eV hydrogen plasma "working fluid" between the liner and the target, and imploding the liner around it. The high initial temperature assures that the sound speed within the liner is always greater than the inner surface implosion velocity of the liner, and the initial density is chosen so that the volume of the working fluid at peak compression is sufficiently large so that perfectly spherical convergence of the liner is not required. One concern with such an approach is that energy losses associated with ionization and radiation will degrade the effective gamma of the compression. To isolate and, therefore, understand these effects we have developed a simple "zero-dimensional" model for the liner implosion that accurately accounts for the shape and thickness of the liner as it implodes and compresses the working fluid. Based on simple considerations we make a crude estimate of the range of initial densities of interest for this technique. We then observe that within this density range, for the temperatures of interest, the lines are strongly self-absorbed so that the transport of radiation is dominated by bound-free and free-free processes. This approximate opacity is coupled to the simple model to determine the extent that radiation losses affect implosion dynamics. We find that over the density range of interest radiation loss effects are not significant.

The operational requirements of the AGS (Alternating Gradient Synchrotron) Booster beam position monitor system necessitate the use of electronics with wide dynamic range and broad instantaneous bandwidth. Bunch synchronization is provided by a remote timing sequencer coupled to the local ring electronics via digital fiber-optic links. The sequencer and local ring circuitry work together to provide single turn trajectory or average orbit and intensity information, integrated over 1 to 255 bunches. Test capabilities are included for the purpose of enhancing BPM system accuracy. The authors describe the design of the Booster beam position monitor electronics and present performance details of the front-end processing, acquisition, and timing circuitry. >

A measurement system of the betatron tune is operational at the AGS (Alternating Gradient Synchrotron), and one for the AGS Booster is under development. Both systems use ferrite kicker magnets to excite coherent betatron oscillations. Difference signals are sampled at the revolution frequency and the tune is extracted from a fast Fourier transform. Details of the hardware of both systems are described, as well as all the features of the application program through which the operator interacts with the hardware. The AGS system and the booster system are described. >

Instrumenting the new AGS (Alternating Gradient Synchrotron) Booster required the construction of a great deal of support electronics for many beam monitoring devices. Modules providing generic functions such as amplification, integration, sample and hold, etc., were designed and packaged so as to provide maximum flexibility in the implementation of typical instrumentation tasks. The authors describe these modules and include some specific examples of how they have been combined to perform certain functions. Several unique features of the packaging are described. >

To accelerate both protons and heavy ions, the AGS (Alternating Gradient Synchrotron) booster requires a broadband (multi-octave) beam position monitoring system with a dynamic range spanning several orders of magnitude (2*10/sup 10/ to 1.5*10/sup 13/ particles per pulse). System requirements include the ability to acquire single-turn trajectory and average orbit information with +or-0.1-mm resolution. The design goal of +or-0.5-mm corrected accuracy requires that the detectors have repeatable linear performance after periodic bakeout at 300 degrees C. The system design and capabilities of the booster beam position monitor are described, and initial results are presented. >

Scintillating fiber tracking detectors are being developed for the SDC experiment at Superconducting Super Collider (SSC) and the upgrade of the D0 detector at the Fermilab Tevatron. The many attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. The photodetector of choice is the visible light phonon counter (VLPC), a device which combines high rate capability with high quantum efficiency at visible wavelengths. To realize the high rate capability of the VLPC requires the implementation of a suitable, fast preamplifier. Until recently, studies of fibers and VLPCs with radioactive sources and cosmic rays have been performed under low rate conditions using transimpedance amplifiers (TIAs). The authors report on the response characteristics of a fiber-VLPC system coupled to a variety of fast preamplifiers, including QPA02, VTX, and TVC devices. Their performance is compared with that of a transimpedance amplifier. >

The transfer line that will serve to transport 8 GeV protons from the Booster to the new Fermilab Main Injector has been built using permanent magnets. A total of 46 horizontal bend dipoles and 5 vertical bend dipoles were built for this beamline; 67 gradient magnets were also built. The magnets were built using magnetized strontium ferrite bricks. Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The dipole magnets were built with a mean integrated strength of 0.56954 T-m, and an rms spread of 0.06%. The magnets were thermally cycled from 20/spl deg/C to 0/spl deg/C to condition the ferrite against irreversible thermal losses, and the compensation was measured with a flipcoil. The magnet strength was adjusted by varying the number of bricks installed at the magnet ends. Details of the assembly process and a summary of magnetic measurements are presented here.

The purpose of this new instrument is for probing beam halo and obtaining beam profiles of the resonant extracted beam at the AGS. The device described is a prototype version, to obtain data and prepare for a more permanent device. The goals of the permanent device are to allow emittances of low current, but high intensity slowly extracted beams to be accurately measured and to have a diagnostic for probing the wings of the beam distribution. The device works on secondary emission from thin targets as well as scattering into two scintillator telescopes. The targets are movable over the entire aperture at the device.

The 8 GeV transfer line feeding protons into the new Fermilab Main Injector has been built using strontium ferrite permanent magnets. This article addresses the design and manufacture of the 67 combined function magnets; permanent horizontal and vertical bend dipoles and quadrupoles were also built. The combined function magnets were built with a mean integrated strength at midaperture of 0.56953 T-m (central field nominally 0.15 T), and a gradient of 3.23% per cm relative to the dipole strength (nominal gradient=0.48 T/m). Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The magnets were thermally cycled from 20/spl deg/C to 0/spl deg/C to condition the ferrite against irreversible thermal losses; the compensation was measured with a flipcoil and verified with a rotating harmonics coil. We present details of the magnet assembly process and also summarize the magnetic measurements.

A wide band, digital damper system has been developed and is in use at the Brookhaven Alternating Gradient Synchrotron (AGS). The system consists of vertical and horizontal capacitive pickups, analog and digital processing electronics, four 500 Watt wide band power amplifiers, and two pairs of strip line beam kickers. The system is currently used to damp transverse coherent instabilities and injection errors, in both planes, for protons and all species of heavy ions. This paper discusses the system design and operation, particularly with regard to stabilization of the high intensity proton beam. The analog and digital signal processing techniques used to achieve optimum results are discussed. Operational data showing the effect of the damping is presented.

There has been a rapid increase in the world-wide application of photovoltaics as a local power source to the utilities. To achieve this DC/AC power conversion is required and has resulted in a number of different power electronic solutions. The vast majority of these employ a 'H' bridges connected to the power network that can be used to unfold a rectified sinewave of current into the network or indeed generate a sinewave of current from a DC source. In the latter case the 'H' bridge devices carry bi-directional current i.e. through the switch and its body diode. The input stage to the inverter is required to boost the PV array voltage and provide electrical isolation. There are a wide variety of possible circuit topologies that may be used. This paper provides the analysis for a number of these that will allow the designer to establish values for the active and passive circuit elements including electromagnetics and thermal considerations. This analysis is incorporated into a PC package using Visual Basic and running under Windows. The format of this is based on a 'question and answer' approach, which allows the users to make design decisions such as operating temperatures etc. and input data of available components. Examples of the Visual Basic display are provided as well as SPICE based verification of some of the analysis used. It is anticipated that the tool will be expanded to include a wider range of input stages in the near future.

The growth hormone secretagogue receptor (GHS-R) is involved in the regulation of pulsatile GH release. However, until recently, natural endogenous ligands for the receptor were unknown. We fractionated porcine hypothalamic extracts and assayed fractions for activity on HEK293 cells expressing GHS-R and aequorin. A partial agonist was isolated and identified using microspray tandem mass spectrometry as adenosine. GHS-R activation by adenosine and synthetic adenosine agonists is inhibited by the GHS-R selective antagonists L-765,867, D-Lys 3 -GHRP-6, and by theophylline and XAC. Cross desensitization of the GHS-R occurs with both MK-0677 and adenosine. Ligand binding and site directed mutagenesis studies show that adenosine binds to a binding site that is distinct from the previously characterized MK-0677 and GHRP-6 binding pocket. We propose, that adenosine is a physiologically important endogenous GHS-R ligand and speculate that GHS-R ligands modulate dopamine release from hypothalamic neurons.

The design and construction of a modular electronic photovoltaic (PV) simulator is presented. This is to be used to develop a reliable and repeatable methodology for the assessment of maximum power point tracking (MPPT) performance. As part of the design process the simulator was modelled using Ispice and Simulink. A linearised model was derived which is used to obtain an optimal compromise between accuracy and dynamic performance for the controller.

A new technique for recoating optical fiber with a polyimide jacket is demonstrated. Single layer coatings of 7 micrometers , and double layers of 15 micrometers have been applied to 125 micrometers fiber. The coatings are uniform and concentric, and can be applied with no loss of original fiber strength. The technique accommodates multiple fiber diameters without the need for interchanging parts.

There has been recent interest in the application of heat engines for conversion of different forms of heat source into electrical energy. One of the favoured forms of heat engine is the Stirling engine. he best way to commercialise the engine is to look for applications where conventional engines cannot compete. So an engine capable of operating from unusual energy sources, may find wide application. The need, then, is to solve the problems associated with electrical generation from such engines. A variety of generators have been used including DC, induction and synchronous types. Engine speeds are not usually constant and some form of power conditioning based on power electronics will be necessary to provide for stand-alone and/or grid-connected operation. The authors discuss the principles of the Stirling engine, combined heat and power systems using heat engines, the electrical generation aspects, and the power electronics interface for 3- and single-phase PM generators. The power converter adopted is a boost converter input stage and an H bridge output stage.

We report on a search for metastable positively and negatively charged states of strange quark matter in Au+Pb reactions at 11.6 A GeV/c in experiment E864. We have sampled approximately six billion 10% most central Au+Pb interactions and have observed no strangelet states (baryon number A < 100 droplets of strange quark matter). We thus set upper limits on the production of these exotic states at the level of 1-6 x 10^{-8} per central collision. These limits are the best and most model independent for this colliding system. We discuss the implications of our results on strangelet production mechanisms, and also on the stability question of strange quark matter., 21 pages, 9 figures, to be published in Nuclear Physics A (Carl Dover memorial edition)

We present a review of results from E760, a resonant charmonium formation experiment in the Fermilab Antiproton Accumulator. Experiment E835, a continuation of E760, and its physics goals are also presented.

A 96-channel, 3-superlayer, scintillating-fiber tracking system has been tested in a 5 GeV/ cπ − beam. The scintillating fibers were 830 μm in diameter, spaced 850 μm apart, and 4.3 m in length. They were coupled to 6 m long, clear fiber waveguides and finally to visible light photon counters. A spatial resolution of ∼ 150 μm for a double-layered ribbon was achieved with this tracking system. This first prototype of a charged-particle tracking system configured for the Solenoidal Detector Collaboration at the Superconducting Super Collider is a benchmark in verifying the expected number of photoelectrons from the fibers.

This report discusses the following topics on the Soleoidal Detector Collaboration: Summary and overview of the detector; physics and detector requirements; central tracking system; superconducting magnet; calorimetry; muon system; electronics; online computing; offline computing; safety; experimental facilities; installation; test and calibration beam plan; and cost and schedule summary.

Increasing numbers of photovoltaic arrays are being connected to the power utility through power electronic inverters. This has raised potential problems of network protection. If, due to the action of the inverter or inverters, the local network voltage and frequency remain within regulatory limits when the utility is disconnected, then islanding is said to occur. Many methods to prevent this have been proposed and a SPICE-based model and analysis of the system are presented. Specifically aimed at predicting the effectiveness of two of these. These are: active frequency drift, which causes the inverter current to be generated slightly lower or higher in frequency than the frequency of the terminal voltage; and slip mode frequency shift, which controls the phase angle of the inverter current as a function of the frequency deviation of the terminal voltage from that of the normal network frequency. Experimental verification of the model is provided. Active frequency drift using frequency speed-up rather than speed-down is shown to be preferable for inductive loads, but conditions that resulted in islanding could be predicted. Slip mode frequency shift proved to be a more robust anti-islanding protection technique.

A new technique for recoating optical fibre with a polyimide jacket is demonstrated and characterised. Single and double layer coatings of 7 and 15 /spl mu/m, respectively, have been applied to 85 and 125 /spl mu/m fibre. The coatings are uniform and pinhole free, and the recoated sections have demonstrated high strength.