The Influence of Shaping Air Pressure of Pneumatic Spray Gun

Science.gov (United States)

Chen, Wenzhuo; Chen, Yan; Pan, Haiwei; Zhang, Weiming; Li, Bo

2018-02-01

The shaping air pressure is a very important parameter in the application of pneumatic spray gun, and studying its influence on spray flow field and film thickness distribution has practical values. In this paper, Euler-Lagrangian method is adopted to describe the two-phase spray flow of pneumatic painting process, and the air flow fields, spray patterns and dynamic film thickness distributions were obtained with the help of the computational fluid dynamics code—ANSYS Fluent. Results show that with the increase of the shaping air pressure, the air phase flow field spreads in the plane perpendicular to the shaping air hole plane, the spray pattern becomes narrower and flatter, and the width of the dynamic film increases with the reduced maximum value of the film thickness. But the film thickness distribution seems to change little with the shaping air pressure decreasing from 0.6bar to 0.9bar.

Pressure cycling induced modification of a cemented carbide

International Nuclear Information System (INIS)

Beste, U.; Engqvist, H.; Jacobson, S.

2001-01-01

The wear of cemented carbide rock drill buttons is due to a complex mixture of mechanisms. One important of such mechanism is the surface fatigue that occurs due to the percussive conditions of rock drilling. To isolate the effects of this mechanism, a mechanical pressure cycling test has been performed on a cemented carbide with 11 % Co and 2 μm WC grain size. The test was ended after 60000 pressure cycles. No signs of fatigue crack nucleation were found. The changes in hardness, fracture toughness, erosion resistance, magnetical coercivity and thermal shock resistance were measured. The microstructure of the sample was investigated with x-ray diffraction, plus scanning and transmission electron microscopy. The fracture toughness decreased 14 % due to the pressure cycling while the hardness did not change. In addition, the thermal shock resistance and the erosion resistance decreased. The magnetical coercivity increased 90 % indicating significant phase transformations or high defect density in the Co binder phase. The TEM revealed no deformation of the WC phase, but important alterations of the Co phase. The Co phase was transformed from fcc into a new unidentified phase, characterized by atomic inter planar distance present in fcc and hcp plus an unfamiliar distance of 2.35 Aa. This phase is suggested to be due to a more complex stacking sequence of the close-packed planes than in hcp or fcc. (author)

Effect of fabrication pressure on the fatigue performance of Cemex XL acrylic bone cement.

Science.gov (United States)

Lewis, Gladius; Janna, S I

2004-01-01

During a cemented arthroplasty, the prepared polymerizing dough of acrylic bone cement is subjected to pressurization in a number of ways; first, during delivery into the freshly prepared bone bed, second, during packing in that bed (either digitally or with the aid of a mechanical device), and, third, during the insertion of the prosthesis. Only a few studies have reported on the influence of the level of pressurization experienced during these events (which, depending on the cementing technique used, has been put at between 8 and 273 kPa) on various properties of the cement. That was the focus of the present study, in which the fully reversed tension-compression (+/-15 MPa; 5 Hz) fatigue lives (expressed as number of cycles to fracture, N(f)) of rectangular cross-sectioned "dog-bone" specimens (Type V, per ASTM D 638) fabricated from Cemex XL cement, at pressure applied continuously to the cement dough during curing in the specimen mold, p=75,150, and 300 kPa, were determined. The N(f) results were analyzed using the linearized transformation of the three-parameter Weibull relationship to obtain estimates of the Weibull mean, N(WM), which was taken to be the index of fatigue performance of the specimen set. Over the range of p studied, N(WM) increased as p increased (for example, from 329,118 cycles when p was 75 kPa to 388,496 cycles when p was 300 kPa); however, the increase was not significant over any pair of p increment steps (Mann-Whitney U-test; alpha<0.05).

Unsteady flow analysis of combustion processes in a Davis gun

Energy Technology Data Exchange (ETDEWEB)

Cho, H.-C.; Shin, H.D. [Korea Advanced Inst. of Science and Technology, Mechanical Engineering Dept., Taejon (Korea, Republic of); Yoon, J.-K. [Hansung Univ., School of Industrial and System Engineering, Seoul (Korea, Republic of)

1999-09-01

The Davis gun, a type of recoilless gun, had the advantages of requiring less rear area and less powder than a conventional recoilless gun. The unsteady pressure and flow fields of a Davis gun were numerically simulated by using a two-phase fluid dynamic model. Numerical simulation results were compared with experimental values to evaluate the feasibility of the interior ballistic model. The interior ballistics in a Davis gun with a simple countermass were predicted with the computational model. It was shown that the pressure-time curves matched well between experimental data and numerical analysis except in the vicinity of the peak pressure and steep pressure gradient. The predicted muzzle velocity of projectile and countermass was closely similar to the experimental one. In this study, large pressure waves were not observed since the initial porosity was relatively high ({phi}{sub 0}0.867) and the charge was ignited at the centre of the granular bed. (Author)

The differences between soil grouting with cement slurry and cement-water glass slurry

Science.gov (United States)

Zhu, Mingting; Sui, Haitong; Yang, Honglu

2018-01-01

Cement slurry and cement-water glass slurry are the most widely applied for soil grouting reinforcement project. The viscosity change of cement slurry is negligible during grouting period and presumed to be time-independent while the viscosity of cement-water glass slurry increases with time quickly and is presumed to be time-dependent. Due to the significantly rheology differences between them, the grouting quality and the increasing characteristics of grouting parameters may be different, such as grouting pressure, grouting surrounding rock pressure, i.e., the change of surrounding rock pressure deduced by grouting pressure. Those are main factors for grouting design. In this paper, a large-scale 3D grouting simulation device was developed to simulate the surrounding curtain grouting for a tunnel. Two series of surrounding curtain grouting experiments under different geo-stress of 100 kPa, 150 kPa and 200 kPa were performed. The overload test on tunnel was performed to evaluate grouting effect of all surrounding curtain grouting experiments. In the present results, before 240 seconds, the grouting pressure increases slowly for both slurries; after 240 seconds the increase rate of grouting pressure for cement-water glass slurry increases quickly while that for cement slurry remains roughly constant. The increasing trend of grouting pressure for cement-water glass is similar to its viscosity. The setting time of cement-water glass slurry obtained from laboratory test is less than that in practical grouting where grout slurry solidifies in soil. The grouting effect of cement-water glass slurry is better than that of cement slurry and the grouting quality decreases with initial pressure.

Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

Science.gov (United States)

Robert, E.; Sarron, V.; Riès, D.; Dozias, S.; Vandamme, M.; Pouvesle, J.-M.

2012-06-01

An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 107-108 cm s-1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications.

Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

International Nuclear Information System (INIS)

Robert, E; Sarron, V; Riès, D; Dozias, S; Vandamme, M; Pouvesle, J-M

2012-01-01

An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 10 7 –10 8 cm s −1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications. (paper)

Foamed cement for squeeze cementing low-pressure, highly permeable reservoirs

International Nuclear Information System (INIS)

Chmllowski, W.; Kondratoff, L.B.

1992-01-01

Four different cement squeezing techniques have been used on wells producing from the Keg River formation in the Rainbow Lake area of Alberta, Canada. This paper evaluates 151 cement squeeze treatments performed at 96 wellsites and compares the use of foam cement vs. conventional squeeze treatments and techniques. Discussion includes key aspects, such as candidate selection, slurry design, treatment design, economic evaluation, and operational considerations

Momentum equation for arc-driven rail guns

International Nuclear Information System (INIS)

Batteh, J.H.

1984-01-01

In several models of arc-driven rail guns, the rails are assumed to be infinitely high to simplify the calculation of the electromagnetic fields which appear in the momentum equation for the arc. This assumption leads to overestimates of the arc pressures and accelerations by approximately a factor of 2 for typical rail-gun geometries. In this paper, we develop a simple method for modifying the momentum equation to account for the effect of finite-height rails on the performance of the rail gun and the properties of the arc. The modification is based on an integration of the Lorentz force across the arc cross section at each axial location in the arc. Application of this technique suggests that, for typical rail-gun geometries and moderately long arcs, the momentum equation appropriate for infinite-height rails can be retained provided that the magnetic pressure term in the equation is scaled by a factor which depends on the effective inductance of the gun. The analysis also indicates that the magnetic pressure gradient actually changes sign near the arc/projectile boundary because of the magnetic fields associated with the arc current

Electron guns for accelerators

International Nuclear Information System (INIS)

Rangarajan, L.M.; Mahadevan, S.; Ramamurthi, S.S.

1995-01-01

The high voltage, high current electron guns developed elsewhere for Linacs are based on cathode pulsing with direct emitting cathodes. Our grid pulsed triode gun employs indirect emitting cathode pellet under electron bombardment or a direct cathode emitter. Electron beam from the gun is injected to the accelerator guide at 40 kV and pulse duration is 2.8μsec. The gun is limited to axially symmetric geometry and electron optical design is optimized by computer programming. The gun with a water cooled Faraday cup is connected to a vacuum system comprising of a sputter ion pump and sorption pump. Working pressure is 1x10 -6 Pa. Gun is designed to be baked as an assembly at temperatures of 400 degC while vacuum processing. Materials are therefore restricted to refractory metals, SS, OFHC copper and all the electrodes are housed inside a ceramic tube. Lower Z graphite is used as a base material of Faraday cup. Grid is non-intercepting modulator anode, a new feature introduced, as compared to meshed grid system by others. CAT gun delivers 160 mA current pulses at 40 kV and its working characteristics such as perveance, emittance and beam radius compare well with SLAC and Hermosa guns. The above guns can be used for electron beam machines such as medical Linacs, industrial accelerators and EB welding equipment. (author). 2 refs., 2 figs

Efficiency of low versus high airline pressure in stunning cattle with a pneumatically powered penetrating captive bolt gun.

Science.gov (United States)

Oliveira, Steffan Edward Octávio; Gregory, Neville George; Dalla Costa, Filipe Antonio; Gibson, Troy John; Paranhos da Costa, Mateus José Rodrigues

2017-08-01

The efficiency of stunning cattle was assessed in 443 animals (304 pure Zebu and 139 crossbred cattle), being mainly mature bulls and cows. Cattle were stunned using a Jarvis pneumatically powered penetrating captive bolt gun operating with low (160-175psi, N=82) and high (190psi, N=363) airline pressure, which was within the manufactures specifications. Signs of brain function and the position of the shots on the heads were recorded after stunning. Velocity of the captive bolt and its physical parameters were calculated. Cattle shot with low pressures showed more rhythmic respiration (27 vs. 8%, P<0.001), less tongue protrusion (4 vs. 12%, P=0.03) and less masseter relaxation (22 vs. 48%, P<0.001). There was an increased frequency of shots in the ideal position when cattle were shot with the low compared to high airline pressures (15.3 vs. 3.1%). Bolt velocity and its physical parameters were significantly (P<0.01) higher when using high pressure. Airline pressures below 190psi are inappropriate when shooting adult Zebu beef cattle with pneumatically powered penetrating captive bolt guns. Copyright © 2017 Elsevier Ltd. All rights reserved.

Results from AFWL 230 kJ coaxial plasma gun experiments

International Nuclear Information System (INIS)

Hall, D.J.; Baker, W.L.; Beason, J.D.; Clouse, C.J.; Degnan, J.H.; Dietz, D.; Hackett, K.E.; Higgins, P.L.; Holmes, J.L.; Price, D.W.

1988-01-01

A coaxial plasma gun has been operated on the AFWL 0.5 MJ capacitor bank. A Marshall valve actuated by an explosive detonator is used to puff hydrogen gas from a small high pressure plenum into the breech of the gun. After a set delay from the explosion the capacitor bank is discharged across the electrodes of the coaxial gun. The operating mode of the gun can be changed by varying the plenum pressure and the firing delay. Over 150 shots have been fired, varying delay, plenum pressure, and initial stored energy. Initial plenum pressures were varied from 250 to 750 psi, and firing delays ranged from 0.8 msec to 2.2 msec. Experiments were conducted at 90, 176, and 230 kJ of initial stored energy (50, 70, adn 80 kV charge). Rogowski coils were used to measure current and magnetic field within the plasma at 25 axial locations along the gun. The coils were installed in grooves on the inner surface of the outer conductor. Signals from the coils were passively integrated. Integrator time constants ranged from 95 to 114 μsec. Time histories of magnetic field profiles are presented. These are used to describe the operating mode of the gun

Hard-driven rail-gun tests

International Nuclear Information System (INIS)

Peterson, D.R.; Adams, D.F.; Cummings, C.E.; Fowler, C.M.; Kerrisk, J.F.; Marsh, S.P.; Parker, J.V.

1983-01-01

A number of prototype rail-gun designs have been tested, powered by explosive magnetic flux compression generators. Peak currents as high as 1.3 MA were delivered. Rail guns with 50-mm-thick Kevlar fiberwound structural shells were able to survive these high currents with minimum mechanical damage and were refired after enlarging the bores 0.2 to 0.4 mm to remove arc damage. In some tests, mechanical damage occurred that was apparently caused by the rebound of the gun after firing. Although the Kevlar shells had more than adequate strength, they appeared to lack sufficient stiffness, allowing excessive deflections. The use of a steel structural shell with a Kevlar sleeve was an improvement. Intrusion into the seams of the rail guns and condensation of material from the plasma armature were observed. Improved sealing of seams is indicated. In some cases, we suspect maldistribution of current within the gun; that is, not all the current delivered to the breech of the gun seemed to reach the plasma armature. Experiments are being designed to quantify the effects discussed. Rail guns of advanced design are being fabricated. An 18-g titanium projectile was accelerated to 2.4 km/s in a 16-mm-round-bore, 0.6-m-long gun, 4-6 g polycarbonate projectiles were accelerated to 3.5 km/s in 13-mm-square-bore, 1.2-m-long rail guns. All tests were conducted at atmospheric pressure

Gun ownership and social gun culture.

Science.gov (United States)

Kalesan, Bindu; Villarreal, Marcos D; Keyes, Katherine M; Galea, Sandro

2016-06-01

We assessed gun ownership rates in 2013 across the USA and the association between exposure to a social gun culture and gun ownership. We used data from a nationally representative sample of 4000 US adults, from 50 states and District of Columbia, aged >18 years to assess gun ownership and social gun culture performed in October 2013. State-level firearm policy information was obtained from the Brady Law Center and Injury Prevention and Control Center. One-third of Americans reported owning a gun, ranging from 5.2% in Delaware to 61.7% in Alaska. Gun ownership was 2.25-times greater among those reporting social gun culture (PR=2.25, 95% CI 2.02 to 2.52) than those who did not. In conclusion, we found strong association between social gun culture and gun ownership. Gun cultures may need to be considered for public health strategies that aim to change gun ownership in the USA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Water gun vs air gun: A comparison

Science.gov (United States)

Hutchinson, D.R.; Detrick, R. S.

1984-01-01

The water gun is a relatively new marine seismic sound source that produces an acoustic signal by an implosive rather than explosive mechanism. A comparison of the source characteristics of two different-sized water guns with those of conventional air guns shows the the water gun signature is cleaner and much shorter than that of a comparable-sized air gun: about 60-100 milliseconds (ms) for an 80-in3. (1.31-liter (I)) water gun compared with several hundred ms for an 80-in3. (1.31-1) air gun. The source spectra of water guns are richer in high frequencies (>200 Hz) than are those of air guns, but they also have less energy than those of air guns at low frequencies. A comparison between water gun and air gun reflection profiles in both shallow (Long Island Sound)-and deep (western Bermuda Rise)-water settings suggests that the water gun offers a good compromise between very high resolution, limited penetration systems (e.g. 3.5-kHz profilers and sparkers) and the large volume air guns and tuned air gun arrays generally used where significant penetration is required. ?? 1984 D. Reidel Publishing Company.

Large Bore Powder Gun Qualification (U)

Energy Technology Data Exchange (ETDEWEB)

Rabern, Donald A. [Los Alamos National Laboratory; Valdiviez, Robert [Los Alamos National Laboratory

2012-04-02

A Large Bore Powder Gun (LBPG) is being designed to enable experimentalists to characterize material behavior outside the capabilities of the NNSS JASPER and LANL TA-55 PF-4 guns. The combination of these three guns will create a capability to conduct impact experiments over a wide range of pressures and shock profiles. The Large Bore Powder Gun will be fielded at the Nevada National Security Site (NNSS) U1a Complex. The Complex is nearly 1000 ft below ground with dedicated drifts for testing, instrumentation, and post-shot entombment. To ensure the reliability, safety, and performance of the LBPG, a qualification plan has been established and documented here. Requirements for the LBPG have been established and documented in WE-14-TR-0065 U A, Large Bore Powder Gun Customer Requirements. The document includes the requirements for the physics experiments, the gun and confinement systems, and operations at NNSS. A detailed description of the requirements is established in that document and is referred to and quoted throughout this document. Two Gun and Confinement Systems will be fielded. The Prototype Gun will be used primarily to characterize the gun and confinement performance and be the primary platform for qualification actions. This gun will also be used to investigate and qualify target and diagnostic modifications through the life of the program (U1a.104 Drift). An identical gun, the Physics Gun, will be fielded for confirmatory and Pu experiments (U1a.102D Drift). Both guns will be qualified for operation. The Gun and Confinement System design will be qualified through analysis, inspection, and testing using the Prototype Gun for the majority of process. The Physics Gun will be qualified through inspection and a limited number of qualification tests to ensure performance and behavior equivalent to the Prototype gun. Figure 1.1 shows the partial configuration of U1a and the locations of the Prototype and Physics Gun/Confinement Systems.

ION GUN

Science.gov (United States)

Dandl, R.A.

1961-10-24

An ion gun is described for the production of an electrically neutral ionized plasma. The ion gun comprises an anode and a cathode mounted in concentric relationship with a narrow annulus between. The facing surfaces of the rear portions of the anode and cathode are recessed to form an annular manifold. Positioned within this manifold is an annular intermediate electrode aligned with the an nulus between the anode and cathode. Gas is fed to the manifold and an arc discharge is established between the anode and cathode. The gas is then withdrawn from the manifold through the annulus between the anode and cathode by a pressure differential. The gas is then ionized by the arc discharge across the annulus. The ionized gas is withdrawn from the annulus by the combined effects of the pressure differential and a collimating magnetic field. In a 3000 gauss magnetic field, an arc voltage of 1800 volts, and an arc current of 0.2 amp, a plasma of about 3 x 10/sup 11/ particles/cc is obtained. (AEC)

The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

International Nuclear Information System (INIS)

Cornish, S.; Khachan, J.

2016-01-01

A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required. (paper)

The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

Science.gov (United States)

Cornish, S.; Khachan, J.

2016-02-01

A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required.

Dynamic Response and Fracture of Composite Gun Tubes

Directory of Open Access Journals (Sweden)

Jerome T. Tzeng

2001-01-01

Full Text Available The fracture behavior due to dynamic response in a composite gun tube subjected to a moving pressure has been investigated. The resonance of stress waves result in very high amplitude and frequency strains in the tube at the instant and location of pressure front passage as the velocity of the projectile approaches a critical value. The cyclic stresses can accelerate crack propagation in the gun tube with an existing imperfection and significantly shorten the fatigue life of gun tubes. The fracture mechanism induced by dynamic amplification effects is particularly critical for composite overwrap barrels because of a multi-material construction, anisotropic material properties, and the potential of thermal degradation.

The use of additive ceramic hollow spheres on cement slurry to prevent lost circulation in formation `X' having low pressure fracture

Science.gov (United States)

Rita, Novia; Mursyidah, Syahindra, Michael

2018-03-01

When drilling, if the hydrostatic pressure is higher than formation pressure (fracture pressure) it will cause lost circulation during cementing process. To solve this problem, hydrostatic pressure of slurry can be decreased by lowering the slurry density by using some additives. Ceramic Hollow Spheres (CHS) is lightweight additive. This additive comes with low specific gravity so it can lowered the slurry density. When the low-density slurry used in cementing process, it can prevent low circulation and fractured formation caused by cement itself. Class G cement is used in this experiment with the standard density of this slurry is 15.8 ppg. With the addition of CHS, slurry density lowered to 12.5 ppg. CHS not only used to lower the slurry density, it also used to make the same properties with the standard slurry even the density has been lowered. Both thickening time and compressive strength have not change if the CHS added to the slurry. With addition of CHS, thickening time at 70 Bc reached in 03 hours 12 minutes. For the compressive strength, 2000 psi reached in 07 hours 07 minutes. Addition of CHS can save more time in cementing process of X formation.

Gun Control, Gun Ownership, and Suicide Prevention.

Science.gov (United States)

Lester, David

1988-01-01

Explored relationship between the extent of gun ownership and the strictness of gun control laws to suicide and homicide rates in the nine major geographic regions of the United States. Found gun ownership, rather than the strictness of gun control laws, was the strongest correlate of the rates of suicide and homicide by guns. (Author)

Study and development of a two-stage light gas gun

International Nuclear Information System (INIS)

Lezaud, Jean-Michel

1976-01-01

After recalling the definition of principal dimensional internal characteristics of a light gas gun studied and developed at Commissariat a l'Energie Atomique, we present the interior ballistics calculation systems in fixed working conditions: these conditions permit to accelerate a 400 g projectile to 6500 m/s speed. About these conditions is studied the influence of some operating parameters: weight of piston, initial pressure of hydrogen, breaking pressure of diaphragms. Afterwards is presented a study of dynamic axial stresses. The consequence of these stresses in certain cross sections of gun has led to conceive the original solution of gun called gun sliding launching tube. At last, some special points appropriated to operating or working methods (optimisation of convergent, extrusion of piston, failure of diaphragms, position of target, circuits of fluids) are presented. (author) [fr

Compact streak camera for the shock study of solids by using the high-pressure gas gun

Science.gov (United States)

Nagayama, Kunihito; Mori, Yasuhito

1993-01-01

For the precise observation of high-speed impact phenomena, a compact high-speed streak camera recording system has been developed. The system consists of a high-pressure gas gun, a streak camera, and a long-pulse dye laser. The gas gun installed in our laboratory has a muzzle of 40 mm in diameter, and a launch tube of 2 m long. Projectile velocity is measured by the laser beam cut method. The gun is capable of accelerating a 27 g projectile up to 500 m/s, if helium gas is used as a driver. The system has been designed on the principal idea that the precise optical measurement methods developed in other areas of research can be applied to the gun study. The streak camera is 300 mm in diameter, with a rectangular rotating mirror which is driven by an air turbine spindle. The attainable streak velocity is 3 mm/microsecond(s) . The size of the camera is rather small aiming at the portability and economy. Therefore, the streak velocity is relatively slower than the fast cameras, but it is possible to use low-sensitivity but high-resolution film as a recording medium. We have also constructed a pulsed dye laser of 25 - 30 microsecond(s) in duration. The laser can be used as a light source of observation. The advantage for the use of the laser will be multi-fold, i.e., good directivity, almost single frequency, and so on. The feasibility of the system has been demonstrated by performing several experiments.

Grip-pattern recognition: Applied to a smart gun

NARCIS (Netherlands)

Shang, X.

2008-01-01

In our work the verification performance of a biometric recognition system based on grip patterns, as part of a smart gun for use by the police ocers, has been investigated. The biometric features are extracted from a two-dimensional pattern of the pressure, exerted on the grip of a gun by the hand

Whose guns are stolen? The epidemiology of Gun theft victims.

Science.gov (United States)

Hemenway, David; Azrael, Deborah; Miller, Matthew

2017-12-01

Gun theft is an important source of guns used by criminals. Yet no empirical work has focused on the characteristics of gun owners that distinguish those who have had their guns stolen from those who have not. In this study, we examine the demographics and behavioral characteristics of gun owners who report having had a gun stolen. Data come from a nationally representative probability-based online survey conducted in April 2015, with a linked follow-up survey in November 2015 that asked gun owners about any theft of their guns in the past 5 years. Of 1,604 gun-owning respondents, 2.4% (95% CI 1.6,3.6) reported that one or more guns had been stolen, with a mean number of guns stolen per theft of 1.5 (95% CI 1.0,2.0]. Risk factors for having a gun stolen were owning 6 or more guns, owning guns for protection, carrying a gun in the past month, storing guns unsafely, and living in the South region of the United States. The South accounts for 37% of US households, 43% of gun owners, and two-thirds of all gun thefts. We estimate that there are approximately 250,000 gun theft incidents per year, with about 380,000 guns stolen. We find that certain types of gun owners-who own many guns, who carry guns, and who do not store guns safely-are at higher risk to have their guns stolen. Tracing data show that states in the South are exporters of crime guns used in other states. Our survey results find that the majority of guns stolen in the US come from the South.

Influence of atmospheric pressure low-temperature plasma treatment on the shear bond strength between zirconia and resin cement.

Science.gov (United States)

Ito, Yuki; Okawa, Takahisa; Fukumoto, Takahiro; Tsurumi, Akiko; Tatsuta, Mitsuhiro; Fujii, Takamasa; Tanaka, Junko; Tanaka, Masahiro

2016-10-01

Zirconia exhibits excellent strength and high biocompatibility in technological applications and it is has therefore been investigated for clinical applications and research. Before setting prostheses, a crown prosthesis inner surface is sandblasted with alumina to remove contaminants and form small cavities. This alumina sandblasting causes stress-induced phase transition of zirconia. Atmospheric-pressure low-temperature plasma has been applied in the dental industry, particularly for adhesives, as a surface treatment to activate the surface energy and remove contaminants. The purpose of this study was to examine the influence of atmospheric-pressure low-temperature plasma treatment on the shear bond strength between zirconia and adhesive resin cement. The surface treatment method was classified into three groups: untreated (Cont group), alumina sandblast treatment (Sb group), and atmospheric-pressure low-temperature plasma treatment (Ps group). Adhesive resin cement was applied to stainless steel and bonded to zirconia. Shear adhesion tests were performed after complete hardening of the cement. Multiple comparisons were performed using a one-way analysis of variance and the Bonferroni method. X-ray diffractometry was used to examine the change in zirconia crystal structure. Statistically significant differences were noted between the control and Sb groups and between the control and Ps groups. In contrast, no statistically significant differences were noted for the Ps and Sb bond strength. Atmospheric-pressure low-temperature plasma treatment did not affect the zirconia crystal structure. Atmospheric-pressure low-temperature plasma treatment improves the bonding strength of adhesive resin cement as effectively as alumina sandblasting, and does not alter the zirconia crystal structure. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Lake Wobegon’s Guns: Overestimating Our Gun-Related Competences

Directory of Open Access Journals (Sweden)

Emily Stark

2016-02-01

Full Text Available The Lake Wobegon Effect is a general tendency for people to overestimate their own abilities. In this study, the authors conducted a large, nationally-representative survey of U.S. citizens to test whether Americans overestimate their own gun-relevant personality traits, gun safety knowledge, and ability to use a gun in an emergency. The authors also tested how gun control attitudes, political identification, gender, and gun experience affect self-perceptions. Consistent with prior research on the Lake Wobegon Effect, participants overestimated their gun-related competencies. Conservatives, males, and pro-gun advocates self-enhanced somewhat more than their counterparts but this effect was primarily due to increased gun experience among these participants. These findings are important to policymakers in the area of gun use, because overconfidence in one’s gun-related abilities may lead to a reduced perceived need for gun training.

Coaxial gun parameters and X-ray emission

International Nuclear Information System (INIS)

Soliman, H.M.; El-Aragi, G.M.; Saudy, A.H.; Masoud, M.M.

1994-01-01

The paper presents the results of investigation with 3 kJ coaxial plasma gun, which operated with argon gas at pressure 0.8 torr. The coaxial plasma gun parameters are investigated by pick up coils, double electric probe, and x-ray probe. The mean electron temperature and density of the ejected plasma are 25 eV and 10 15 cm -3 respectively. The maximum kinetic pressure of the ejected plasma in the expansion chamber appears after 10 μs from the start of the discharge current. The energetic electrons is detected by an x-ray probe which showed a single pulse of electrons with energy ≅ 3 Kev. (orig.)

Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 kms

Science.gov (United States)

Bogdanoff, David W.

2016-01-01

Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 11 kms and as high as 15 kms. For debris shield design, it would be desirable to be able to launch controlled shape projectiles to these velocities. The design of the proposed 10 11 kmsec gun uses, as a starting point, the Ames 1.280.22 two stage gun, which has achieved muzzle velocities of 10 11.3 kmsec. That gun is scaled up to a 0.3125 launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (LD), the piston mass and the hydrogen pressure. A pump tube LD of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be 2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube LD of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.7 10.8 kmsec, and that disc-like plastic models could be launched to 11.05 kms. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 kms.

Plasma focusing in coaxial gun

International Nuclear Information System (INIS)

Soliman, H.M.; Masoud, M.M.; El-Khalafawy, T.

1986-01-01

A capacitor bank has been discharged between two coaxial electrodes of 6.6 cm outer diameter, 3.2 cm inner diameter and length of 31.5 cm. filled with hydrogen gas at pressure of 310 μHg. Results show that, the axial and radial plasma current reach a maximum value at a position adjacent to the gun muzzle, at which the plasma focus occurs. The measurement of the electron temperature and density and azimuthal electric field along the axis of the expansion chamber, gives a maximum value at z∼18 cm from the gun muzzle, while the axial plasma current and velocity has a minimum value at that position. These results indicate that a second point of a plasma focus has been formed at z∼18 cm from the gun muzzle, along the axis of the expansion chamber

Development of the Antares electron gun

International Nuclear Information System (INIS)

Stine, R.; Leland, W.; Mansfield, C.; Rosocha, L.; Jansen, J.; Gibson, R.; Allen, G.

1984-01-01

Antares is the Los Alamos National Laboratory 40-kJ, 1-ns, CO 2 laser system that is now operational. This laser system was developed for the Intertial Confinement Fusion (ICF) program and is beginning target experiments. The distributed circuit modeling, design and operation of the large electron gun developed for the final laser power amplifier are reviewed. This gun is significant because of the large electron current area, 9 m 2 ; the number of emitter blades, 48; the dual cathode current return; and the coaxial geometry and grid control. The gun components and their development are discussed. These include the emitter blades, the coaxial grid (to maintain constant electron current during the 5-μs pulse), the bonded stacked-ring insulator (to electrically insulate the grid/cathode), the Kapton/aluminum electron transmission windows (to provide an interface between gun vacuum and laser gas) and the vacuum shell (operated at a vacuum of 10 -6 torr). A unique pressure diagnostic is also discussed

Repetitive, small-bore two-stage light gas gun

International Nuclear Information System (INIS)

Combs, S.K.; Foust, C.R.; Fehling, D.T.; Gouge, M.J.; Milora, S.L.

1991-01-01

A repetitive two-stage light gas gun for high-speed pellet injection has been developed at Oak Ridge National Laboratory. In general, applications of the two-stage light gas gun have been limited to only single shots, with a finite time (at least minutes) needed for recovery and preparation for the next shot. The new device overcomes problems associated with repetitive operation, including rapidly evacuating the propellant gases, reloading the gun breech with a new projectile, returning the piston to its initial position, and refilling the first- and second-stage gas volumes to the appropriate pressure levels. In addition, some components are subjected to and must survive severe operating conditions, which include rapid cycling to high pressures and temperatures (up to thousands of bars and thousands of kelvins) and significant mechanical shocks. Small plastic projectiles (4-mm nominal size) and helium gas have been used in the prototype device, which was equipped with a 1-m-long pump tube and a 1-m-long gun barrel, to demonstrate repetitive operation (up to 1 Hz) at relatively high pellet velocities (up to 3000 m/s). The equipment is described, and experimental results are presented. 124 refs., 6 figs., 5 tabs

Class H cement hydration at 180 deg. C and high pressure in the presence of added silica

International Nuclear Information System (INIS)

Jupe, Andrew C.; Wilkinson, Angus P.; Luke, Karen; Funkhouser, Gary P.

2008-01-01

Under deep oil-well conditions of elevated temperature and pressure, crystalline calcium silicate hydrates are formed during Portland cement hydration. The use of silica rich mineral additives leads to the formation of crystalline hydrates with better mechanical properties than those formed without the additive. The effects of silica flour, silica fume (amorphous silica), and a natural zeolite mixture on the hydration of Class H cement slurries at 180 deg. C under externally applied pressures of 7 and 52 MPa are examined in real time using in-situ synchrotron X-ray diffraction. For some compositions examined, but not all, pressure was found to have a large effect on the kinetics of crystalline hydrate formation. The use of silica fume delayed both C 3 S hydration and the formation of crystalline silicate hydrates compared to what was seen with other silica sources

Gun Play

Science.gov (United States)

Mechling, Jay

2008-01-01

Biology and the particular gun culture of the United States come together to explain the persistent and powerful attraction of American boys to both real guns and toy guns. The 1990s saw adults begin to conflate "the gun problem" with "the boy problem," sparking attempts (largely failed) to banish toy guns from homes and…

DC-driven plasma gun: self-oscillatory operation mode of atmospheric-pressure helium plasma jet comprised of repetitive streamer breakdowns

Science.gov (United States)

Wang, Xingxing; Shashurin, Alexey

2017-02-01

This paper presents and studies helium atmospheric pressure plasma jet comprised of a series of repetitive streamer breakdowns, which is driven by pure DC high voltage (self-oscillatory behavior). The repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV cm-1. One type of the helium plasma gun designed using this operational principle is demonstrated. The gun operates on about 3 kV DC high voltage and is comprised of the series of the repetitive streamer breakdowns at a frequency of about 13 kHz.

Numerical simulation of two-piston light gas gun for pellet injection in tokamaks

International Nuclear Information System (INIS)

Shi Yumei; He Yaling; Chen Zhongqi; Wu Peiyi

1995-01-01

Analysing the shortcoming of the single-piston light gas gun, the author uses the method of characteristics to estimate the performance of the two-piston light gas gun, and compare it with the single-piston gun, the result shows that two-piston gun has advantage on the aspect of the pressure pulse that promotes the pellet. The effects of some important parameters are also discussed. This work provides the theoretical basis for the design and optimization of two-piston light gas gun

Progress on Using NEA Cathodes in an RF Gun

CERN Document Server

Fliller, Raymond P; Blüm, Hans; Edwards, Helen; Hüning, Markus; Schultheiss, Tom; Sinclair, Charles K

2005-01-01

RF guns have proven useful in multiple accelerator applications, and are an attractive electron source for the ILC. Using a NEA GaAs photocathode in such a gun allows for the production of polarized electron beams. However the lifetime of a NEA cathode in this environment is reduced by ion and electron bombardment and residual gas oxidation. We report progress made with studies to produce a RF gun using a NEA GaAs photocathode to produce polarized electron beams. Attempts to reduce the residual gas pressure in the gun are discussed. Initial measurements of ion flux through the cathode port are compared with simulations of ion bombardment. Future directions are also discussed.

Deposition of SiOx on Metal Surface with a DBD Plasma Gun at Atmospheric Pressure for Corrosion Prevention

International Nuclear Information System (INIS)

Han Erli; Chen Qiang; Zhang Yuefei; Chen Fei; Ge Yuanjing

2007-01-01

In this study, SiO x films were deposited by a dielectric barrier discharge (DBD) plasma gun at an atmospheric pressure. The relationship of the film structures with plasma powers was investigated by Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). It was shown that an uniform and cross-linking structure film was formed by the DBD gun. As an application, the SiO x films were deposited on a carbon steel surface for the anti-corrosion purpose. The experiment was carried out in a 0.1 M NaCl solution. It was found that a very good anti-corrosive property was obtained, i.e., the corrosion rate was decreased c.a. 15 times in 5% NaCl solution compared to the non-SiO x coated steel, as detected by the potentiodynamic polarization measurement

Very low pressure plasma sprayed yttria-stabilized zirconia coating using a low-energy plasma gun

International Nuclear Information System (INIS)

Zhu, Lin; Zhang, Nannan; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

2011-01-01

In the present study, a more economical low-energy plasma source was used to perform a very low pressure plasma-spray (VLPPS) process. The plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Moreover, yttria-stabilized zirconia coating (YSZ) was elaborated by a F100 low-power plasma gun under working pressure of 1 mbar, and the substrate specimens were partially shadowed by a baffle-plate during plasma spraying for obtaining different coating microstructures. Based on the SEM observation, a column-like grain coating was deposited by pure vapor deposition at the shadowed region, whereas, in the unshadowed region, the coating exhibited a binary microstructure which was formed by a mixed deposition of melted particles and evaporated particles. The mechanical properties of the coating were also well under investigation. (orig.)

Experimental Study on Artificial Cemented Sand Prepared with Ordinary Portland Cement with Different Contents

Directory of Open Access Journals (Sweden)

Dongliang Li

2015-07-01

Full Text Available Artificial cemented sand test samples were prepared by using ordinary Portland cement (OPC as the cementing agent. Through uniaxial compression tests and consolidated drained triaxial compression tests, the stress-strain curves of the artificial cemented sand with different cementing agent contents (0.01, 0.03, 0.05 and 0.08 under various confining pressures (0.00 MPa, 0.25 MPa, 0.50 MPa and 1.00 MPa were obtained. Based on the test results, the effect of the cementing agent content (Cv on the physical and mechanical properties of the artificial cemented sand were analyzed and the Mohr-Coulomb strength theory was modified by using Cv. The research reveals that when Cv is high (e.g., Cv = 0.03, 0.05 or 0.08, the stress-strain curves of the samples indicate a strain softening behavior; under the same confining pressure, as Cv increases, both the peak strength and residual strength of the samples show a significant increase. When Cv is low (e.g., Cv = 0.01, the stress-strain curves of the samples indicate strain hardening behavior. From the test data, a function of Cv (the cementing agent content with c′ (the cohesion force of the sample and Δϕ′ (the increment of the angle of shearing resistance is obtained. Furthermore, through modification of the Mohr-Coulomb strength theory, the effect of cementing agent content on the strength of the cemented sand is demonstrated.

Experimental Study on Artificial Cemented Sand Prepared with Ordinary Portland Cement with Different Contents.

Science.gov (United States)

Li, Dongliang; Liu, Xinrong; Liu, Xianshan

2015-07-02

Artificial cemented sand test samples were prepared by using ordinary Portland cement (OPC) as the cementing agent. Through uniaxial compression tests and consolidated drained triaxial compression tests, the stress-strain curves of the artificial cemented sand with different cementing agent contents (0.01, 0.03, 0.05 and 0.08) under various confining pressures (0.00 MPa, 0.25 MPa, 0.50 MPa and 1.00 MPa) were obtained. Based on the test results, the effect of the cementing agent content ( C v ) on the physical and mechanical properties of the artificial cemented sand were analyzed and the Mohr-Coulomb strength theory was modified by using C v . The research reveals that when C v is high (e.g., C v = 0.03, 0.05 or 0.08), the stress-strain curves of the samples indicate a strain softening behavior; under the same confining pressure, as C v increases, both the peak strength and residual strength of the samples show a significant increase. When C v is low (e.g., C v = 0.01), the stress-strain curves of the samples indicate strain hardening behavior. From the test data, a function of C v (the cementing agent content) with c ' (the cohesion force of the sample) and Δϕ' (the increment of the angle of shearing resistance) is obtained. Furthermore, through modification of the Mohr-Coulomb strength theory, the effect of cementing agent content on the strength of the cemented sand is demonstrated.

Gun Shows and Gun Violence: Fatally Flawed Study Yields Misleading Results

Science.gov (United States)

Hemenway, David; Webster, Daniel; Pierce, Glenn; Braga, Anthony A.

2010-01-01

A widely publicized but unpublished study of the relationship between gun shows and gun violence is being cited in debates about the regulation of gun shows and gun commerce. We believe the study is fatally flawed. A working paper entitled “The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas” outlined this study, which found no association between gun shows and gun-related deaths. We believe the study reflects a limited understanding of gun shows and gun markets and is not statistically powered to detect even an implausibly large effect of gun shows on gun violence. In addition, the research contains serious ascertainment and classification errors, produces results that are sensitive to minor specification changes in key variables and in some cases have no face validity, and is contradicted by 1 of its own authors’ prior research. The study should not be used as evidence in formulating gun policy. PMID:20724672

Encyclopedia of Gun Control and Gun Rights.

Science.gov (United States)

Utter, Glenn H.

This reference volume provides information on gun control and gun rights, including resources on the debate surrounding the Second Amendment and individuals and organizations focused on gun issues, along with statutes, court cases, events, and publications surrounding this current topic. Highlighted are the important organizations and their…

Practical XHV electron gun

International Nuclear Information System (INIS)

Urata, Tomohiro; Ishikawa, Tsuyoshi; Cho, Boklae; Oshima, Chuhei

2008-01-01

We have developed practical XHV chambers of a electron gun, of which the operating pressures are 1x10 -9 Pa in a stainless-steel one and 4x10 -9 Pa in a permalloy one. By mounting a noble single-atom electron source with high brightness and high spatial coherence on the electron gun including electron optics, we demonstrated highly collimated electron-beam emission: ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources. In XHV, in addition, we confirmed stable electron emission up to 20 nA, which results in the specimen current high enough for scanning electron microscopes. (author)

Low-energy plasma-cathode electron gun with a perforated emission electrode

Science.gov (United States)

Burdovitsin, Victor; Kazakov, Andrey; Medovnik, Alexander; Oks, Efim; Tyunkov, Andrey

2017-11-01

We describe research of influence of the geometric parameters of perforated electrode on emission parameters of a plasma cathode electron gun generating continuous electron beams at gas pressure 5-6 Pa. It is shown, that the emission current increases with increasing the hole diameters and decreasing the thickness of the perforated emission electrode. Plasma-cathode gun with perforated electron can provide electron extraction with an efficiency of up to 72 %. It is shown, that the current-voltage characteristic of the electron gun with a perforated emission electrode differs from that of similar guns with fine mesh grid electrode. The plasma-cathode electron gun with perforated emission electrode is used for electron beam welding and sintering.

Electrical properties of a co-axial plasma gun

International Nuclear Information System (INIS)

Allam, T.M.Y.

1997-01-01

The main interest of this work is to study the power discharge of capacitor bank through a coaxial electrodes system. Such arrangement is called the coaxial gun or coaxial accelerator. It is used in jet propulsion and in triggering of discharge in turbo engines or in plasma combustion arrangement. The main goal is to find out the efficiency of the system in both cases. coaxial plasma gun system has been constructed for this course of study. The plasma gun system consists of the plasma gun tube and the discharge chamber, the capacitor bank, the triggering system the vacuum system, the power supply, and safety and dumping system. Simple and efficient diagnostic techniques were used to measure the different parameters concerning the coaxial discharge system such as the Rogowski loop, the voltage divider, the magnetic probes, the double electric probe. Results were obtained using argon gas with an operating pressure ranging from 0.1 torr to 1 torr. The peak discharge current in the first half cycle was 44 K A with rise time of 6.25 μs for a bank charging voltage of 10 kv and gas pressure of 0.9 torr. 4-26 figs., 4-8 tabs., 33 refs

State Gun Law Environment and Youth Gun Carrying in the United States.

Science.gov (United States)

Xuan, Ziming; Hemenway, David

2015-11-01

Gun violence and injuries pose a substantial threat to children and youth in the United States. Existing evidence points to the need for interventions and policies for keeping guns out of the hands of children and youth. (1) To examine the association between state gun law environment and youth gun carrying in the United States, and (2) to determine whether adult gun ownership mediates this association. This was a repeated cross-sectional observational study design with 3 years of data on youth gun carrying from US states. The Youth Risk Behavior Survey comprises data of representative samples of students in grades 9 to 12 from biennial years of 2007, 2009, and 2011. We hypothesized that states with more restrictive gun laws have lower rates of youth gun carrying, and this association is mediated by adult gun ownership. State gun law environment as measured by state gun law score. Youth gun carrying was defined as having carried a gun on at least 1 day during the 30 days before the survey. In the fully adjusted model, a 10-point increase in the state gun law score, which represented a more restrictive gun law environment, was associated with a 9% decrease in the odds of youth gun carrying (adjusted odds ratio [AOR], 0.91 [95% CI, 0.86-0.96]). Adult gun ownership mediated the association between state gun law score and youth gun carrying (AOR, 0.94 [ 95% CI, 0.86-1.01], with 29% attenuation of the regression coefficient from -0.09 to -0.07 based on bootstrap resampling). More restrictive overall gun control policies are associated with a reduced likelihood of youth gun carrying. These findings are relevant to gun policy debates about the critical importance of strengthening overall gun law environment to prevent youth gun carrying.

A high-power millimeter wave driven steam gun for pellet injectors

International Nuclear Information System (INIS)

Itoh, Yasuyuki

1997-01-01

A concept of steam gun is proposed for using in two-stage pneumatic hydrogen isotope pellet injectors. The steam gun is driven by megawatt-level high-power millimeter waves (∼100 GHz) supplied by gyrotrons. A small amount of water is injected into its pump tube. The water is instantaneously heated by the millimeter waves and vaporized. Generated high-pressure steam accelerates a piston for compressing light gas to drive a frozen pellet. Discussions in this paper concentrate on the piston acceleration. Results show that 1 MW millimeter waves accelerate the 25 g piston to velocities of ∼200 m/s in a 1 m-long pump tube. The piston acceleration characteristics are not improved in comparison to light gas guns with first valves. The steam gun concept, however, avoids the use of a large amount of high-pressure gas for piston accelerations. In future fusion reactors, gyrotrons used during preionization and start-up phase would be available for producing required millimeter waves. (author)

Development techniques and electron optical studies of high voltage, high current electron guns

International Nuclear Information System (INIS)

Rangarajan, L.M.; Mahadevan, S.; Ramamurthi, S.S.

1992-01-01

The progress of the electron gun design, limiting to axially symmetric geometries is discussed here with a view to utilise such guns for electron accelerators. The mechanical design features leading to the physical configuration of the gun with stringent tolerances are outlined. Vacuum processing is done at pressures of 1.3x10 -5 Pa. The gun employs W-filament emitter or a cathode pellet with bombarder service. A water cooled compact faraday cup is used to measure the electron current. Electron gun geometries have been studied using the computer programme. The preveance of the gun is 0.7x10 -7 A/Vsup(1.5) at 80 kV. Developmental techniques of such pulsed electron guns are described. (author). 7 refs., 5 figs

Design of a high repetition rate S-band photocathode gun

International Nuclear Information System (INIS)

Han Janghui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji

2011-01-01

Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ-ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported. - Highlights: → We design an S-band gun for low emittance beam generation and high repetition rate operation. → The RF design and thermal analysis of the gun cavity and coupler are studied. → An FEL injector is designed by using this gun and the beam dynamics simulation is shown. → A cold test with a prototype gun for confirmation of the RF design is reported.

Lifetime measurements using the Jefferson Lad Load-Lock Electron Gun

International Nuclear Information System (INIS)

J. Grames; P. Adderley; M. Baylac; J. Brittian; D. Charles; J. Clark; J. Hansknecht; M. Poelker; M. Stutzman; K. Surles-Law

2000-01-01

Lifetime measurements of bulk GaAs using a 100 kV load-lock electron gun and beam line were made. Initial tests used anodized samples to study lifetime under various conditions (gun vacuum, laser spot location, activated area). Subsequent tests used a mechanical mask to limit the active area and included improved monitoring of the gun chamber and beam line vacuum pressure. Results of these measurements support claims made at past workshops, namely photocathode lifetime improves when gun vacuum is enhanced and when electron emission from the edge of the photocathode is eliminated. The dependence upon laser spot location is less certain. Tests studying lifetime at higher beam intensity (I ∼ 8 mA) have begun

Polymer-cement interactions towards improved wellbore cement fracture sealants

Science.gov (United States)

Beckingham, B. S.; Iloejesi, C.; Minkler, M. J.; Schindler, A. K.; Beckingham, L. E.

2017-12-01

Carbon capture, utilization, and storage (CCUS) in deep geologic formations is a promising means of reducing point source emissions of CO2. In these systems, CO2 is captured at the source and then injected to be utilized (eg. in enhanced oil recovery or as a working fluid in enhanced geothermal energy plants) or stored in geologic formations such as depleted oil and gas reservoirs or saline aquifers. While CCUS in subsurface systems could aid in reducing atmospheric CO2 emissions, the potential for CO2 leakage from these systems to overlying formations remains a major limitation and poses a significant risk to the security of injected CO2. Thus, improved materials for both initial wellbore isolation and repairing leakage pathways that develop over time are sought. One approach for the repair of cement fractures in wellbore (and other) systems is the injection of polymer materials into the fracture with a subsequent environmentally dependent (temperature, pressure, pH, etc.) densification or solidification. Here, we aim to investigate novel polymer materials for use to repair leaking wellbores in the context of CCUS. We synthesize and fully characterize a series of novel polymer materials and utilize a suite of analysis techniques to examine polymer-cement interactions at a range of conditions (namely temperature, pressure and pH). Initial findings will be leveraged to design novel polymer materials for further evaluation in polymer-cement composite cores, cement fracture healing, and the aging behavior of healed cements.

Development of plasma cathode electron guns

Science.gov (United States)

Oks, Efim M.; Schanin, Peter M.

1999-05-01

The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

Through BHA (Bottom Hole Assembly) cementing with proprietary cementing technology

Energy Technology Data Exchange (ETDEWEB)

Fanguy, Charles ' Joey' ; Mueller, Dan T. [BJ Services Company, Houston, TX (United States); Garrett, J.C. [Palm Energy Partners, LLC, Metairie, LA (United States)

2004-07-01

There are many problems that can arise when drilling into sub-normally pressured or naturally fractured zones. Lost circulation is one problem that is commonly encountered while drilling oil and gas wells. Lost circulation can lead to increased costs associated with drilling due to rig time, spreadsheet costs, and expensive mud system losses. Cement is one of the most effective treatment options, although it is not normally considered the first option because most operators are forced to trip out of the wellbore and utilize a squeeze packer. This is not always a viable option because of potential well control issues associated with the hydrostatic pressure reduction due to the losses of the whole mud. One treatment option that is commonly overlooked is pumping cement slurries through the bottom hole assembly and drill bit. This is generally not attempted for a variety of reasons. These reasons include: I Concern about 'squeezing off' of the cement in the bit II Lack of potential quality control associated with mixing 'on the fly' III Lack of the ability to test the actual mixed slurry samples The use of a pre-mixed, storable cement slurry has eliminated the concerns associated with pumping cement slurries through mud motors, MWD tools, BHA's, and drill bits. This advanced cement technology has been successfully utilized while reducing the risks associated with these lost circulation treatments. In addition, this technology has eliminated the costs associated with using a squeeze packer and the rig time required for several trips out of the wellbore. The paper will describe the premixed slurry properties and QA/QC procedures that are required for successful through the bit operations. This paper will also provide case histories of successful through the bit operation, as well as background information leading to the treatments. The case histories include successful through the bit remediation of severe lost circulation zones and as well the

Electromagnetic Guns versus Conventional Guns - a performance comparison

NARCIS (Netherlands)

Reus, N.M. de; Weijden, J. van der

1993-01-01

Performance improvement is one of the key issues of Electromagnetic gun systems compared to conventional gun systems. Due to higher muzzle velocities, the gun's fire control computer will be able to predict the target's future position more accurately because prediction time will be smaller. In this

Electron gun for the positron generator

International Nuclear Information System (INIS)

Fukuda, S.; Ogawa, Y.; Saito, Y.

1986-01-01

A triode electron gun has been installed on the Positron Generator at KEK, and brought into test operation. It involves a grid-cathode assembly currently used in a planner triode. The cathode has a diameter of 10 mm and is coated with Ba-Sr-Ca oxide. Because of the short grid-cathode distance (0.18 mm), the relatively low grid pulse voltages makes it possible to draw a high current. The assembly has a small vacuum flange which allows its easy replacement. Emission current from the oxide cathode is sensitive to residual gases, therefore, the vacuum system is carefully made and the pressure is kept in the range of 10 -9 Torr even when the accelerator is on. The grid pulser is a line type pulser using multi-stage avalanche transistors as a switch. The pulse width of 10 nsec has been used for the test to investigate the gun characteristics. The performance of the gun has been tested with this pulser and the emission current of 9.7 A was achieved at an injection voltage of 110 kV. The characteristics of the gun are described together with the beam trace

Gas-gun facility for shock wave research at BARC

International Nuclear Information System (INIS)

Gupta, S.C.; Jyoti, G.; Suresh, N.; Sikka, S.K.; Chidambaram, R.; Agarwal, R.G.; Roy, S.; Kakodkar, A.

1995-01-01

For carrying out shock-wave experiments on materials, we have built a 63 mm diameter gas-gun facility at our laboratory. It is capable of accelerating projectiles (about half kg in weight) to velocities up to 1 km/s using N 2 and He gases. These on impacting a target generate shock pressures up to 40 GPa, depending upon the impedance of the impactor and the target. The barrel of the gun is slotted so that a keyed projectile can be fired for combined compression- shear studies. Large samples can be shocked (about 60 mm diameter and 5-10 mm thick), with pressures lasting for a few microseconds. The gun is similar in design to the one at Washington State University. A number of diagnostic techniques have also been developed. These include measurement of projectile velocity, tilt between the impactor and the target, shock velocity in the target, and time resolved in-material stress wave histories in the shock loaded samples. Recovery capsules have also been made to retrieve shocked samples on unloading, which are then analysed using microscopic techniques like x-ray diffraction, Raman and electron microscopy. The gun has been performing well and has already been used for a few phase transition studies. (author). 73 refs., 42 figs

The Effects of Gun Ownership Rates and Gun Control Laws on Suicide Rates

OpenAIRE

Mark Gius

2011-01-01

The purpose of the present study is to determine the effects of gun control laws and gun ownership rates on state-level suicide rates. Using the most recent data on suicide rates, gun control measures, and gun ownership rates, the results of the present study suggest that states that require handgun permits have lower gun-related suicide rates, and states that have higher gun ownership rates have higher gun-related suicide rates. Regarding non-gun suicides, results suggest that stricter gun c...

Environmental impacts of air-gun surveys on glass sponges : final report

Energy Technology Data Exchange (ETDEWEB)

Tunnicliffe, V; Yahel, G [Victoria Univ., Victoria, BC (Canada). Dept. of Biology; Chapman, R; Wilmut, M [Victoria Univ., Victoria, BC (Canada). School of Earth and Ocean Sciences

2008-09-15

Air-gun surveys associated with the oil and gas exploration in the Queen Charlotte Basin will insonify the seafloor with broadband, high intensity noise, exposing the glass sponge reef systems of that area to acoustic impacts. Tissue integrity and behaviour of marine animals can be affected by the acoustic harassment of water propagated vibration. This paper examined the effects of acoustic noise on the behaviour of glass sponges. The purpose of the study was to test the hypothesis that the acoustic vibration produced by a small, surface operated air gun would not alter the normal pattern of sponge feeding activities. The paper described the methods, with particular reference to the study site; sponge pumping rate; and acoustic effects on sponge pumping. Results were presented for ambient conditions; air gun shots; sponge pumping responses to air gun shots; and correlation of sponge response and ambient current. The question of whether the sponge's excurrent flow responds to the pressure from a series of air-gun shots was addressed by a statistical analysis over all the excurrent data from the experiment. It was concluded that there is little or no evidence that the acoustic pressure from the shots influences the physiological functions of the sponge. 22 refs., 2 tabs., 11 figs.

Environmental impacts of air-gun surveys on glass sponges : final report

Energy Technology Data Exchange (ETDEWEB)

Tunnicliffe, V.; Yahel, G. [Victoria Univ., Victoria, BC (Canada). Dept. of Biology; Chapman, R.; Wilmut, M. [Victoria Univ., Victoria, BC (Canada). School of Earth and Ocean Sciences

2008-09-15

Air-gun surveys associated with the oil and gas exploration in the Queen Charlotte Basin will insonify the seafloor with broadband, high intensity noise, exposing the glass sponge reef systems of that area to acoustic impacts. Tissue integrity and behaviour of marine animals can be affected by the acoustic harassment of water propagated vibration. This paper examined the effects of acoustic noise on the behaviour of glass sponges. The purpose of the study was to test the hypothesis that the acoustic vibration produced by a small, surface operated air gun would not alter the normal pattern of sponge feeding activities. The paper described the methods, with particular reference to the study site; sponge pumping rate; and acoustic effects on sponge pumping. Results were presented for ambient conditions; air gun shots; sponge pumping responses to air gun shots; and correlation of sponge response and ambient current. The question of whether the sponge's excurrent flow responds to the pressure from a series of air-gun shots was addressed by a statistical analysis over all the excurrent data from the experiment. It was concluded that there is little or no evidence that the acoustic pressure from the shots influences the physiological functions of the sponge. 22 refs., 2 tabs., 11 figs.

Gun Safety

Science.gov (United States)

Many U.S. households have guns, but they can cause harm if not handled properly. Here are some things you can do to keep yourself and ... safe: Teach children that they shouldn't touch guns and that if they see a gun, to ...

Highly efficient electron gun with a single-atom electron source

International Nuclear Information System (INIS)

Ishikawa, Tsuyoshi; Urata, Tomohiro; Cho, Boklae; Rokuta, Eiji; Oshima, Chuhei; Terui, Yoshinori; Saito, Hidekazu; Yonezawa, Akira; Tsong, Tien T.

2007-01-01

The authors have demonstrated highly collimated electron-beam emission from a practical electron gun with a single-atom electron source; ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources such as a cold field emission gun and a Zr/O/W Schottky gun. At the pressure of less than 1x10 -9 Pa, the authors observed stable emission of 20 nA, which generates the specimen current of 5 pA required for scanning electron microscopes

Magnetized gun experiments

International Nuclear Information System (INIS)

Jarboe, T.R.; Henins, I.; Hoida, H.W.; Marshall, J.; Sherwood, A.R.

1981-01-01

In the Los Alamos Magnetized Gun Experiment we are attempting to produce a compact torus in a manner similar to an earlier experiment of Alfven. In our experiment a solenoidal coil is placed inside the inner electrode of a coaxial plasma gun. This coil produces an axial magnetic field inside the inner electrode which diverges and becomes a largely radial field in front of the gun muzzle. The idea is that when the gun is fired, the plasma escaping from the gun stretches these radial fields along the axial direction away from the gun, and these field lines can reconnect behind the plasma forming the poloidal field of the compact torus. The magnetic field generated by the gun current becomes the toroidal field and the major axis of the compact torus will be the same as the axis of the coaxial gun. Recent interest in this possible method of compact torus generation was stimulated by C. Hartman, and the approach is also being pursued in the field-reversed plasma gun experiment at LLL

Long pulse, plasma cathode E-gun

International Nuclear Information System (INIS)

Goebel, D.M.; Schumacher, R.W.; Watkins, R.M.

1993-01-01

A unique, long-pulse E-gun has been developed for high-power tube applications. The Hollow-Cathode-Plasma (HCP) E-gun overcomes the limitations of conventional thermionic-cathode guns that have limited current density (typically ≤ 10 A/cm 2 ) or field-emission guns that offer high current density but suffer from short pulsewidth capability (typically 50 A/cm 2 ), long-pulse operation without gap closure, and also requires no cathode-heater power. The gun employs a low-pressure glow discharge inside a hollow cathode (HC) structure to provide a stable, uniform plasma surface from which a high current-density electron beam can be extracted. The plasma density is controlled by a low-voltage HC discharge pulser to produce the desired electron current density at the first grid of a multi-grid accelerator system. A dc high-voltage electron-beam supply accelerates the electrons across the gap, while the HC pulser modulates the beam current to generate arbitrary pulse waveforms. The electron accelerator utilizes a multi-aperture array that produces a large area, high perveance (>35 μpervs) beam consisting initially of many individual beamlets. The E-beam is normally operated without an applied magnetic field in the ion-focused regime, where the plasma produced by beam ionization of a background gas space-charge neutralizes the beam, and the Bennett self-pinch compresses the beamlets and increases the current density. The self-pinched beam has been observed to propagate over a meter without beam breakup or instabilities. The HCP E-gun has been operated at voltages up to 150 kV, currents up to 750 A, and pulse lengths of up to 120 μsec

Characteristics of shock propagation in high-strength cement mortar

Science.gov (United States)

Wang, Zhanjiang; Li, Xiaolan; Zhang, Ruoqi

2001-06-01

Planar impact experiments have been performed on high-strength cement mortar to determine characteristics of shock propagation.The experiments were conducted on a light-gas gun,and permanent-magnet particle velocity gages were used to obtain the sand of 0.5 3.5mm size.A bulk density of 2.31g/cm^3,and a compressive and tensile strength of 82MPa and 7.8MPa,respectively,were determined.Three kinds of experimental techniques were used,including the reverse ballistic configuration.These techniques effectively averaged the measured dynamic compression state over a sensibly large volume of the test sample.The impact velocities were controlled over a range of approximately 80m/s to 0.83km/s.Hugoniot equation of state data were obtained for the material over a pressure range of approximately 0.2 2.0GPa,and its nonlinear constitutive relation were analyzed.The experiment results show that,in higher pressure range provided in the experiment,the shock wave in the material splits into two components of an elastic and a plastic,with the Hugoniot elastic limit 0.4 0.5GPa and the precursor velocity about 4.7km/s,and the material presents a very strong nonlinear dynamic response,and its shock amplitude will greatly decrease in propagation.

Gun Safety (For Kids)

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Gun Safety KidsHealth / For Kids / Gun Safety What's in ... from guns outside the home. If You Have Guns in Your Home If your parents keep guns ...

State Gun Policy and Cross-State Externalities: Evidence from Crime Gun Tracing

OpenAIRE

Brian Knight

2013-01-01

This paper provides a theoretical and empirical analysis of cross-state externalities associated with gun regulations in the context of the gun trafficking market. Using gun tracing data, which identify the source state for crime guns recovered in destination states, we find that firearms in this market tend to flow from states with weak gun laws to states with strict gun laws, satisfying a necessary condition for the existence of cross-state externalities in the theoretical model. We also fi...

Isosteric Vapor Pressure – Temperature Data for Water Sorption in Hardened Cement Paste: Enthalpy, Entropy and Sorption Isotherms at Different Temperatures

DEFF Research Database (Denmark)

Radjy, Fariborz; Sellevold, Erik J.; Hansen, Kurt Kielsgaard

. The accuracies for pressure, enthalpy and entropy are found to be 0.5% or less. PART II: The TPA-system has been used to generate water vapor pressure – temperature data for room temperature – and steam cured hardened cement pastes as well as porous vycor glass. The moisture contents range from saturated to dry...... and the temperatures range from 2 to 95 °C, differing for the specimen types. The data has been analyzed to yield differential enthalpy and entropy of adsorption, as well as the dependence of the relative vapor pressure on temperature at various constant moisture contents. The implications for the coefficient......PART I: In order to generate isosteric (constant mass) vapor pressure – temperature data (P-T data) for adsorbed pore water in hydrated cement paste, the Thermo Piestic Analysis system (the TPA system) described herein was developed. The TPA system generates high precision equilibrium isosteric P...

Triaxial shear behavior of a cement-treated sand–gravel mixture

Directory of Open Access Journals (Sweden)

Younes Amini

2014-10-01

Full Text Available A number of parameters, e.g. cement content, cement type, relative density, and grain size distribution, can influence the mechanical behaviors of cemented soils. In the present study, a series of conventional triaxial compression tests were conducted on a cemented poorly graded sand–gravel mixture containing 30% gravel and 70% sand in both consolidated drained and undrained conditions. Portland cement used as the cementing agent was added to the soil at 0%, 1%, 2%, and 3% (dry weight of sand–gravel mixture. Samples were prepared at 70% relative density and tested at confining pressures of 50 kPa, 100 kPa, and 150 kPa. Comparison of the results with other studies on well graded gravely sands indicated more dilation or negative pore pressure in poorly graded samples. Undrained failure envelopes determined using zero Skempton's pore pressure coefficient (A¯=0 criterion were consistent with the drained ones. Energy absorption potential was higher in drained condition than undrained condition, suggesting that more energy was required to induce deformation in cemented soil under drained state. Energy absorption increased with increase in cement content under both drained and undrained conditions.

Temporal association between federal gun laws and the diversion of guns to criminals in Milwaukee.

Science.gov (United States)

Webster, Daniel W; Vernick, Jon S; Bulzacchelli, Maria T; Vittes, Katherine A

2012-02-01

The practices of licensed gun dealers can threaten the safety of urban residents by facilitating the diversion of guns to criminals. In 2003, changes to federal law shielded gun dealers from the release of gun trace data and provided other protections to gun dealers. The 14-month period during which the dealer did not sell junk guns was associated with a 68% reduction in the diversion of guns to criminals within a year of sale by the dealer and a 43% increase in guns diverted to criminals following sales by other dealers. The laws were associated with a 203% increase in the number of guns diverted to criminals within a year of sale by the gun store, which was the focus of this study. Policies which affect gun dealer accountability appeared to influence the diversion of guns to criminals.

Is it cement to be? Downhole cement that uses zeolite additive may offer lightweight alternative

Energy Technology Data Exchange (ETDEWEB)

Mahoney, J.

2001-05-01

C2C Zeolite Corporation produces zeolites from a large deposit near Cache Creek, British Columbia, and processes them for use as an additive in downhole cement well casings. Early research indicates that zeolites can significantly improve the way downhole cement is made in the oil industry. Zeolites are made up mostly of silicates of aluminum and calcium. They have a great ability to absorb water, resulting in a lighter and more fluid cement than is currently available. C2C claims that zeolites will reduce cement weight, column pressure and operator costs. The cost benefits of using lighter cement downhole includes easier moving, processing and handling of the mix. Initial research suggests that zeolites might prove to be viable alternatives to other cement lighteners such as silica fumes or flyash. Zeolite-based cement also performed reasonably well in freeze-thaw tests and showed good adhesion and no evidence of shrinkage in downhole tests. 3 figs.

Effects of Exposure to Gun Violence in Movies on Children's Interest in Real Guns.

Science.gov (United States)

Dillon, Kelly P; Bushman, Brad J

2017-11-01

More US children die by accidental gun use than children in other developed countries. One factor that can influence children's interest in guns is exposure to media containing guns. To test whether children who see a movie containing guns will handle a real gun longer and will pull the trigger more times than children who see the same movie not containing guns. One hundred four children aged 8 to 12 years recruited through advertisements were randomly assigned in pairs to watch a 20-minute PG-rated movie containing or not containing guns in a university laboratory. Children then played with toys and games in a room for 20 minutes while being video recorded. A cabinet in the room contained a real (disabled) gun with a sensor counting trigger pulls. Recordings were coded for the time spent holding the gun and in aggressive play. Data were collected from July 15, 2015, through January 1, 2016, and analyzed using generalized estimating equations (Tweedie log-link for time spent holding the gun; Poisson log-link for pulling the trigger). The 2 main outcomes were time spent holding the gun and the number of trigger pulls. Control variables included sex, age, trait aggressiveness, exposure to violent media, interest in guns, and number of guns at home. Among the 104 study participants (62 boys [59.6%] and 42 girls [40.4%]; mean (SD) age, 9.9 [1.5] years), the adjusted median number of trigger pulls among children who saw the movie containing guns was 2.8 (interquartile range [IQR], 0.2-2.8) compared with 0.01 (IQR, 0.01-0.2) among children who saw the movie not containing guns (adjusted odds ratio, 22.3; 95% CI, 6.0-83.4; P gun among children who saw a movie containing guns was 53.1 (IQR, 35.5-53.1) compared with 11.1 (IQR, 10.7-16.7) among children who saw the movie not containing guns (adjusted odds ratio, 3.0; 95% CI, 0.9-9.9; P = .07). Qualitative analyses on 4 pairs from each condition found that children who saw the movie containing guns also played more

God and Guns: Examining Religious Influences on Gun Control Attitudes in the United States

Directory of Open Access Journals (Sweden)

Stephen M. Merino

2018-06-01

Full Text Available Mass shootings in the United States have generated significant media coverage and public concern, invigorating debates over gun control. Media coverage and academic research on gun control attitudes and reactions to mass shootings have paid little attention to the role of religion. Recent research sheds light on the complex relationship between religion and guns, including higher rates of gun ownership and stronger opposition to gun control among white evangelical Protestants. Using nationally representative survey data, this study examines the relationship between religious identity, gun ownership, and support for a range of gun control policies, including proposed remedies for preventing mass shootings. Compared with individuals from other religious traditions, evangelical Protestants are most opposed to stricter gun control laws and enforcement, even with statistical controls for gun ownership and demographic characteristics. Rather, they favor individualistic solutions and putting more emphasis on religious values in their social surroundings. I discuss how these findings reflect the cultural tools evangelical Protestants use to construct their understandings of social problems, including gun violence, and the broader implications for gun policy in the United States.

Gun Theft and Crime.

Science.gov (United States)

Cook, Philip J

2018-06-01

Some law enforcement officials and other observers have asserted that theft is the primary source of guns to crime. In fact, the role of theft in supplying the guns used in robbery, assault, and murder is unknown, and current evidence provides little guidance about whether an effective program to reduce gun theft would reduce gun violence. The current article analyzes publicly available national data on gun theft together with a unique data set for Chicago. The results tend to support a conclusion that stolen guns play only a minor role in crime. First, publicly available data are used to calculate that thefts are only about 1% of all gun transactions nationwide. Second, an analysis of original data from Chicago demonstrates that less than 3% of crime guns recovered by the police have been reported stolen to the Chicago Police Department (CPD). If a gun is reported stolen, there is a 20% chance that it will be recovered, usually in conjunction with an arrest for illegal carrying. Less than half of those picked up with a stolen gun have a criminal record that includes violent offenses. Third, results from surveys of convicted criminals, both nationally and in Chicago, suggest that it is rare for respondents to have stolen the gun used in their most recent crime. The data on which these results are based have various shortcomings. A research agenda is proposed that would provide more certainty about the role of theft.

Guns and Violence. Current Controversies.

Science.gov (United States)

Kim, Henny H., Ed.

This book focuses on gun violence and gun control, presenting both sides of arguments about firearms ownership and gun control. Each of five chapters poses a question about gun control and provides answers for both sides of the question. The following essays are included: (1) "Gun Violence Is Becoming an Epidemic" (Bob Herbert); (2) "Gun Violence…

Solid deuterium pellet injection with a two-stage pneumatic gun

International Nuclear Information System (INIS)

Reggiori, A.; Riva, G.; Daminelli, G.; Frattolillo, A.; Martinis, L.; Scaramuzzi, F.

1989-01-01

Recent results on injection of D 2 pellets, using an improved light gas gun, are reported. In order to overcome the limits imposed by the low mechanical strength of solid hydrogen, a double-piston gun has been developed, in which the pressure pulse can be shaped in different ways, allowing reduction of the maximum acceleration of the pellet. Experiments have been performed with plastic and D 2 pellets. Velocities above 2500 m/s have been obtained with unbroken D 2 pellets

Improving the Performance of Two-Stage Gas Guns By Adding a Diaphragm in the Pump Tube

Science.gov (United States)

Bogdanoff, D. W.; Miller, Robert J.

1995-01-01

Herein, we study the technique of improving the gun performance by installing a diaphragm in the pump tube of the gun. A CFD study is carried out for the 0.28 in. gun in the Hypervelocity Free Flight Radiation (HFF RAD) range at the NASA Ames Research Center. The normal, full-length pump tube is studied as well as two pump tubes of reduced length (approximately 75% and approximately 33% of the normal length). Significant improvements in performance are calculated to be gained for the reduced length pump tubes upon the addition of the diaphragm. These improvements are identified as reductions in maximum pressures in the pump tube and at the projectile base of approximately 20%, while maintaining the projectile muzzle velocity or as increases in muzzle velocity of approximately 0.5 km/sec while not increasing the maximum pressures in the gun. Also, it is found that both guns with reduced pump tube length (with diaphragms) could maintain the performance of gun with the full length pump tube without diaphragms, whereas the guns with reduced pump tube lengths without diaphragms could not. A five-shot experimental investigation of the pump tube diaphragm technique is carried out for the gun with a pump tube length of 75% normal. The CFD predictions of increased muzzle velocity are borne out by the experimental data. Modest, but useful muzzle velocity increases (2.5 - 6%) are obtained upon the installation of a diaphragm, compared to a benchmark shot without a diaphragm.

Gun control saves lives

African Journals Online (AJOL)

gun control legislation. One study estimated that more than 4 500 lives were saved across five SA cities from 2001 to 2005.[5] Pro-gun interest groups seeking to promote gun ownership and diffusion have attacked these findings, suggesting that stricter gun control was only enacted in 2004 following the publication of ...

Gun Sales. Firearm Facts.

Science.gov (United States)

Duker, Laurie, Ed.

Minimal federal regulations on firearm sales have facilitated the proliferation of guns, gun owners, and gun dealers in the United States. This fact sheet offers data on the growing number of firearm dealers, the relative ease of obtaining and keeping a license to sell guns from the Federal Bureau of Alcohol, Tobacco, and Firearms, the lack of…

Heavy cement slurries; Pastas pesadas de cimento

Energy Technology Data Exchange (ETDEWEB)

Silva, Francisco Avelar da; Conceicao, Antonio C. Farias [PETROBRAS, XX (Brazil). Distrito de Perfuracao do Nordeste. Div. de Tecnicas de Perfuracao; Marins, Carlos Cesar Silva [PETROBRAS, XX (Brazil). Dept. de Perfuracao. Div. de Revestimento e Cimentacao

1990-12-31

When going deeper in a high pressure well, the only way to successfully cement your casing or linear is through the use of heavy cement slurry. In 1987 PETROBRAS geologists presented to the Drilling Department a series of deep, hot and high pressure wells to be drilled. The Casing and Cement Division of this department then started a program to face this new challenge. This paper introduces the first part of this program and shows how PETROBRAS is dealing with heavy weight slurries. We present the slurry formulations tested in laboratory, the difficulties found in mixing them in the field, rheology measurements, API free water and API fluid loss from both laboratory and field samples. (author) 3 tabs.

Racism, gun ownership and gun control: biased attitudes in US whites may influence policy decisions.

Science.gov (United States)

O'Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

2013-01-01

Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.

Flexible cement improves wellbore integrity for steam assisted gravity drainage SAGD wells

Energy Technology Data Exchange (ETDEWEB)

DeBruijn, G.; Whitton, S.; Redekopp, D. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Schlumberger Canada Ltd., Calgary, AB (Canada); Siso, C. [ConocoPhillips Canada Resources Corp., Calgary, AB (Canada); Reinheimer, D. [Schlumberger Canada Ltd., Calgary, AB (Canada)

2008-10-15

Cement sheath integrity is an important factor in ensuring the zonal isolation of wells. Significant stresses are placed on the cement sheaths of wells during steam assisted gravity drainage (SAGD) processes, as the expanded forces from the heating of the well are transferred to the cement sheath, which places a tensile load on the cement at the sheath's outer edge. In this study, a computerized simulation was conducted to examine stresses in a novel flexible cement sheath system during an SAGD heat-up cycle. Wellbore temperature was increased from 10 degrees C to 250 degrees C over a period of 720 minutes. Pressure was increased from 0 MPa to 5 MPa. The finite element model was used to predict microannulus, cement failure in compression, and cement failure in tension. A sensitivity analysis was used to estimate the effect of different parameters as well as to estimate the value of the Young's modulus of the shale. Results of the study showed that temperature and pressure dynamics have a significant impact on stresses in the cement sheath. An extended heat-up period resulted in reduced stresses to the sheath. Lower operating pressures also reduced stresses. It was concluded that pressure and temperature increases should be extended over a long a period as possible in order to reduce stresses. Results suggested that a flexible cement system with a low Young's modulus is suitable for SAGD wells. 8 refs., 2 tabs., 6 figs.

Co-axial electrodes gun characteristics

International Nuclear Information System (INIS)

Masoud, M.M.; Soliman, H.M.

1981-01-01

A coaxial electrodes gun is constructed with inner electrode diameter of 3.2 cm; outer electrode diameter of 6.6 cm and length of 25 cm it is connected to a condenser bank which delivers 4 K joule stored energy. The maximum power of the discharge is equal to 4.5x10 4 K watt; for 5 KV charging voltage. The inductance showed two main peak values of 0.257μH and 0.27μH. Theoretical calculations using one-dimension-single fluid model is μ sed, which shows that the maximum acceleration is at 0.5 sec, and the gas breakdown takes place at the gun breech; at the start of the discharge, will leave the gun after 1.625μ sec, also the drift velocity, the force and the magnetic field are given. The measured results show quite reasonable agreement with the calculations for most of the results, and the position of the plasma sheath inside the gun slightly deviated from the theoretical calculations due to viscosity and wall interaction, as well as other parameters which did not be take into consideration. The plasma current density of the sheath has its maximum value at Z=18 cm, the plasma will leave the coaxial source after 1.5μ sec, from the start of the discharge, which conferms with the theoretical model. Resistance of the gas between the electrodes, changes with time according to the particle injected from this source, and the maximum efficiency of the installation for charging voltage 5kV and pressure 80μ Hg is at approx.=10μ sec and 20.5μ sec

Macro-defect free cements. State of art

International Nuclear Information System (INIS)

Holanda, J.N.F.; Povoa, G.E.A.M.; Souza, G.P.; Pinatti, D.G.

1998-01-01

The purpose of this work is to prevent a state of art about macro-defect-free cement pastes (MDF cement ) of high mechanical strength. This new type of cement paste is obtained through addition of a water-soluble polymer, followed by intense shear mixing and application of low compacting pressure. It is presented fundamental aspects related to the processing of this MDF paste, as well as its main properties and applications are discussed. (author)

Racism, gun ownership and gun control: biased attitudes in US whites may influence policy decisions.

Directory of Open Access Journals (Sweden)

Kerry O'Brien

Full Text Available OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty. This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. RESULTS: After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58 was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46, which likely represents self-interest in retaining property (guns. CONCLUSIONS: Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.

Racism, Gun Ownership and Gun Control: Biased Attitudes in US Whites May Influence Policy Decisions

Science.gov (United States)

O’Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

2013-01-01

Objective Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. Method The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. Results After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Conclusions Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites’ paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions. PMID:24204867

Gun power source for electron gun of 3 MeV DC accelerator

International Nuclear Information System (INIS)

Dewangan, S.; Sharma, D.K.; Nanu, K.

2011-01-01

In DC electron beam accelerator electron gun is situated at high voltage terminal which requires constant power irrespective of beam energy. Floating power source is required for gun. This paper describes the scheme of static gun power source derived from parallel coupled voltage multiplier column. (author)

The Influence of the Axial Magnetic Field Upon-the Coaxial Plasma Gun Parameters

International Nuclear Information System (INIS)

El-Aragi, G.M.; EL-Demrdash, A.

2001-01-01

This study concerns with the influence of an applied axial magnetic field upon the electrical parameters of a coaxial plasma gun device. The experimental results are investigated with 0.5 KJ plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied

Study of cements silicate phases hydrated under high pressure and high temperature; Etude des phases silicatees du ciment hydrate sous haute pression et haute temperature

Energy Technology Data Exchange (ETDEWEB)

Meducin, F.

2001-10-01

This study concerns the durability of oil-well cementing. Indeed, in oil well cementing a cement slurry is pumped down the steel casing of the well up the annular space between it and the surrounding rock to support and protect the casing. The setting conditions of pressure and temperature may be very high (up to 1000 bar and 250 deg C at the bottom of the oil-well). In this research, the hydration of the main constituent of cement, synthetic tri-calcium silicate Ca{sub 3}SiO{sub 2}, often called C{sub 3}S (C = CaO; S = SiO{sub 2} and H H{sub 2}O), is studied. Calcium Silicate hydrates are prepared in high-pressure cells to complete their phase diagram (P,T) and obtain the stability conditions for each species. Indeed, the phases formed in these conditions are unknown and the study consists in the hydration of C{sub 3}S at different temperatures, pressures, and during different times to simulate the oil-well conditions. In a first step (until 120 deg C at ambient pressure) the C-S-H, a not well crystallized and non-stoichiometric phase, is synthesized: it brings adhesion and mechanical properties., Then, when pressure and temperature increase, crystallized phases appear such as jaffeite (Ca{sub 6}(Si{sub 2}O{sub 7})(OH){sub 6}) and hillebrandite (Ca{sub 2}(SiO{sub 3})(OH){sub 2}). Silicon {sup 29}Si Nuclear Magnetic Resonance (using standard sequences MAS, CPMAS) allow us to identify all the silicates hydrates formed. Indeed, {sup 29}Si NMR is a valuable tool to determine the structure of crystallized or not-well crystallized phases of cement. The characterization of the hydrated samples is completed by other techniques: X- Ray Diffraction and Scanning Electron Microscopy. The following results are found: jaffeite is the most stable phase at C/S=3. To simulate the hydration of real cement, hydration of C{sub 3}S with ground quartz and with or without super-plasticizers is done. In those cases, new phases appear: kilchoanite mainly, and xonotlite. A large amount of

Carbon plasma gun

International Nuclear Information System (INIS)

Mendel, C.W. Jr.; Zagar, D.M.; Mills, G.S.; Humphries, S. Jr.; Goldstein, S.A.

1980-01-01

A family of plasma guns supplying highly ionized carbon plasma is described. The guns are simple and inexpensive to construct and are pulsed by small capacitor banks of a few hundred joules. The output consists of 10 17 --10 18 multiply ionized carbon ions traveling at about 10 7 cm/s. Neutral output is very low and arrives well after the ionized carbon. The guns and pulsers are very reliable

Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

Science.gov (United States)

Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

2002-05-01

We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

Carbon Nanotube Electron Gun

Science.gov (United States)

Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

2013-01-01

An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DEVILBISS JGHV-531-46FF HVLP SPRAY GUN

Science.gov (United States)

This report presents the results of the verification test of the DeVilbiss JGHV-531-46FF high-volume, low-pressure pressure-feed spray gun, hereafter referred to as the DeVilbiss JGHV, which is designed for use in industrial finishing. The test coating chosen by ITW Industrial Fi...

Design of Fit-for-Purpose Cement to Restore Cement-Caprock Seal Integrity

Science.gov (United States)

Provost, R.

2015-12-01

This project aims to study critical research needs in the area of rock-cement interfaces, with a special focus on crosscutting applications in the Wellbore Integrity Pillar of the SubTER initiative. This study will focus on design and test fit-for-purpose cement formulations. The goals of this project are as follows: 1) perform preliminary study of dispersing nanomaterial admixtures in Ordinary Portland Cement (OPC) mixes, 2) characterize the cement-rock interface, and 3) identify potential high-performance cement additives that can improve sorption behavior, chemical durability, bond strength, and interfacial fracture toughness, as appropriate to specific subsurface operational needs. The work presented here focuses on a study of cement-shale interfaces to better understand failure mechanisms, with particular attention to measuring bond strength at the cement-shale interface. Both experimental testing and computational modeling were conducted to determine the mechanical behavior at the interface representing the interaction of cement and shale of a typical wellbore environment. Cohesive zone elements are used in the finite element method to computationally simulate the interface of the cement and rock materials with varying properties. Understanding the bond strength and mechanical performance of the cement-formation interface is critical to wellbore applications such as sequestration, oil and gas production and exploration and nuclear waste disposal. Improved shear bond strength is an indication of the capability of the interface to ensure zonal isolation and prevent zonal communication, two crucial goals in preserving wellbore integrity. Understanding shear bond strength development and interface mechanics will provide an idea as to how the cement-formation interface can be altered under environmental changes (temperature, pressure, chemical degradation, etc.) so that the previously described objectives can be achieved. Sandia National Laboratories is a multi

Gun Violence, Mental Illness, And Laws That Prohibit Gun Possession: Evidence From Two Florida Counties.

Science.gov (United States)

Swanson, Jeffrey W; Easter, Michele M; Robertson, Allison G; Swartz, Marvin S; Alanis-Hirsch, Kelly; Moseley, Daniel; Dion, Charles; Petrila, John

2016-06-01

Gun violence kills about ninety people every day in the United States, a toll measured in wasted and ruined lives and with an annual economic price tag exceeding $200 billion. Some policy makers suggest that reforming mental health care systems and improving point-of-purchase background checks to keep guns from mentally disturbed people will address the problem. Epidemiological research shows that serious mental illness contributes little to the risk of interpersonal violence but is a strong factor in suicide, which accounts for most firearm fatalities. Meanwhile, the effectiveness of gun restrictions focused on mental illness remains poorly understood. This article examines gun-related suicide and violent crime in people with serious mental illnesses, and whether legal restrictions on firearm sales to people with a history of mental health adjudication are effective in preventing gun violence. Among the study population in two large Florida counties, we found that 62 percent of violent gun crime arrests and 28 percent of gun suicides involved individuals not legally permitted to have a gun at the time. Suggested policy reforms include enacting risk-based gun removal laws and prohibiting guns from people involuntarily detained in short-term psychiatric hospitalizations. Project HOPE—The People-to-People Health Foundation, Inc.

Electromagnetic compression gun for hypervelocity projectile acceleration

International Nuclear Information System (INIS)

Woo, J.T.

1987-01-01

The rapid acceleration of projectiles to very high velocities has applications in many areas. The general requirements for an effective system is simplicity, reliability, compactness and good efficiency. The authors developed a concept by using electromagnetic forces to compressionally heat a plasma to high temperature and pressure to serve as the propellant for the acceleration of projectiles. The concept shares the simplicity of the light gas gun, but because of the high temperature of the propellant, is capable of significantly higher performance. Unlike the electrothermal gun approach to raise the propellant temperature by resistive heating, the electromagnetic concept is more efficient at higher temperatures. Operationally, the concept resembles a railgun in requiring a large pulsed current to drive the system. However, the current flow in this case is entirely external to the gun barrel and is axisymmetric. Therefore, many of the problems associated with railgun operations are avoided. Furthermore, because the current channel is external, there is also greater flexibility in the choice of load impedance to match to the power supply. The concept can also be generalized to a multi-stage regenerative system driven by a pulse forming network to resemble a coaxial accelerator

Sanoli Gun

Indian Academy of Sciences (India)

Home; Journals; Proceedings – Mathematical Sciences. Sanoli Gun. Articles written in Proceedings – Mathematical Sciences. Volume 119 Issue 3 June 2009 pp 275-281. Remarks on some Zero-Sum Theorems · S D Adhikari Sanoli Gun Purusottam Rath · More Details Abstract Fulltext PDF. In the present paper, we give a ...

Modelling porewater chemistry in hydrated Portland cement

International Nuclear Information System (INIS)

Berner, U.R.

1987-01-01

Extensive employment of concrete is foreseen in radioactive waste repositories. A prerequisite for modelling the interactions between concrete and formation waters is characterization of the concrete system. Available experimental data from high pressure squeezing of cement pore-water indicate that, besides the high pH due to alkali hydroxide dissolution, cement composition itself influences the solubility determining solid phases. A model which simulates the hydration of Portland cement assuming complete hydration of the main clinker minerals is presented. The model also includes parameters describing the reactions between the cement and blending agents. Comparison with measured pore-water data generally gives a consistent picture and, as expected, the model gives correct predictions for pure Portland cements. For blended cements, the required additional parameters can, to some extent, be derived from pore-water analysis. 14 references, 1 figure, 4 tables

Dynamic void behavior in polymerizing polymethyl methacrylate cement.

Science.gov (United States)

Muller, Scott D; McCaskie, Andrew W

2006-02-01

Cement mantle voids remain controversial with respect to survival of total hip arthroplasty. Void evolution is poorly understood, and attempts at void manipulation can only be empirical. We induced voids in a cement model simulating the constraints of the proximal femur. Intravoid pressure and temperature were recorded throughout polymerization, and the initial and final void volumes were measured. Temperature-dependent peak intravoid pressures and void volume increases were observed. After solidification, subatmospheric intravoid pressures were observed. The magnitude of these observations could not be explained by the ideal gas law. Partial pressures of the void gas at peak pressures demonstrated a dominant effect of gaseous monomer, thereby suggesting that void growth is a pressure-driven phenomenon resulting from temperature-dependent evaporation of monomer into existing trapped air voids.

Goods for Guns--the use of a gun buyback as an injury prevention/community education tool.

Science.gov (United States)

McGuire, Margaret; Manno, Mariann; Rook, Allison; Maranda, Louise; Renaud, Elizabeth; DeRoss, Anthony; Hirsh, Michael

2011-11-01

US children aged between 5 years and 14 years have a rate of gun-related homicide 17 times higher and a rate of gun-related suicide and unintentional firearm injury 10 times higher than other developed countries. Gun buyback programs have been criticized as ineffective interventions in decreasing violence. The Injury Free Coalition for Kids-Worcester (IFCK-W) Goods for Guns buyback is a multipronged approach to address these concerns and to reduce the number of firearms in the community. The IFCK-W buyback program is funded by corporate sponsors, grants, and individual donations. Citizens are instructed to transport guns, ammunition, and weapons safely to police headquarters on two Saturdays in December. Participants are guaranteed anonymity by the District Attorney's office and receive gift certificates for operable guns. Trained volunteers administer an anonymous survey to willing participants. Individuals who disclose having unsafely stored guns remaining at home receive educational counseling and trigger locks. Guns and ammunition are destroyed at a later time in a gun crushing ceremony. Since 2002, 1,861 guns (444 rifle/shotgun, 738 pistol/revolver, and 679 automatic/semiautomatic) have been collected at a cost of $99,250 (average, $53/gun). Seven hundred ten people have surrendered firearms, 534 surveys have been administered, and ≈ 75 trigger locks have been distributed per year. IFCK-W Goods for Guns is a relatively inexpensive injury prevention model program that removes unwanted firearms from homes, raises community awareness about gun safety, and provides high-risk individuals with trigger locks and educational counseling.

30 CFR 250.1608 - Well casing and cementing.

Science.gov (United States)

2010-07-01

....1608 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND... rock casing (brine wells), and (vi) Production liner. (2) The lessee shall case and cement all wells... the formation pressures and fluids. Cement composition, placement techniques, and waiting time shall...

The Effects of Cueing and Framing on Youth Attitudes towards Gun Control and Gun Rights

Directory of Open Access Journals (Sweden)

Stephen Wu

2018-02-01

Full Text Available I analyze attitudes towards gun control from a recent survey of American high school students. For students who most closely identify as Republicans, cueing them to think about prior school shootings increases their agreement that armed staff in schools will improve safety and arming citizens will reduce risk of mass shootings. For those identifying as Democrats and Independents, providing them with selective information that certain states have loose gun control laws and low rates of gun violence makes them more supportive of gun rights. For Republicans, providing selective information that certain states have loose gun control laws and high rates of gun violence makes them less supportive of gun rights. These results suggest that emotional cues may exacerbate a priori biases, while informational cues may be more likely to change people’s minds about firearm policies.

Computational Fluid Dynamics Application to Gun Muzzle Blast - A Validation Case Study

National Research Council Canada - National Science Library

Cler, Daniel

2003-01-01

...) simulations of these flow-fields a viable alternative. Techniques and specialized CFD codes are being developed in order to properly model the unsteady, very high-pressure flows of gun muzzle blast...

The case for moderate gun control.

Science.gov (United States)

DeGrazia, David

2014-03-01

In addressing the shape of appropriate gun policy, this essay assumes for the sake of discussion that there is a legal and moral right to private gun ownership. My thesis is that, against the background of this right, the most defensible policy approach in the United States would feature moderate gun control. The first section summarizes the American gun control status quo and characterizes what I call "moderate gun control." The next section states and rebuts six leading arguments against this general approach to gun policy. The section that follows presents a positive case for moderate gun control that emphasizes safety in the home and society as well as rights whose enforcement entails some limits or qualifications on the right to bear arms. A final section shows how the recommended gun regulations address legitimate purposes, rather than imposing arbitrary restrictions on gun rights, and offers concluding reflections.

Blower Gun pellet injection system for W7-X

Energy Technology Data Exchange (ETDEWEB)

Dibon, M., E-mail: mathias.dibon@ipp.mpg.de [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Baldzuhn, J.; Beck, M. [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Cardella, A. [Lehrstuhl für Nukleartechnik, TU Munich, Boltzmannstr. 15, 85748 Garching (Germany); Köchl, F. [Atominstitut, TU Wien, 1020 Vienna (Austria); Kocsis, G. [Wigner RCP, RMI, P.O. Box 49, H-1525 Budapest-114 (Hungary); Lang, P.T. [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Macian-Juan, R. [Lehrstuhl für Nukleartechnik, TU Munich, Boltzmannstr. 15, 85748 Garching (Germany); Ploeckl, B. [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Szepesi, T. [Wigner RCP, RMI, P.O. Box 49, H-1525 Budapest-114 (Hungary); Weisbart, W. [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)

2015-10-15

Highlights: • Operational principle of the ASDEX Upgrade Blower Gun. • Guiding tube properties for pellet guiding according to the requirements of W7-X. • Diagnostics for the characterization of the injection system. • Experimental procedure to investigate the performance of the Blower Gun. • Results concerning pellet speeds, mass loss, delivery efficiency and exit angle. - Abstract: Foreseen to perform pellet investigations in the new stellarator W7-X, the former ASDEX Upgrade Blower Gun was revised and revitalized. The systems operational characteristics have been surveyed in a test bed. The gun is designed to launch cylindrical pellets with 2 mm diameter and 2 mm length, produced from frozen deuterium D{sub 2}, hydrogen H{sub 2} or a gas mixture consisting of 50% H{sub 2} and 50% D{sub 2}. Pellets are accelerated by a short pulse of pressurized helium propellant gas to velocities in the range of 100–250 m/s. Delivery reliabilities at the launcher exit reach almost unity. The initial pellet mass is reduced to about 50% during the acceleration process. Pellet transfer to the plasma vessel was investigated by a first mock up guiding tube version. Transfer through this S-shaped stainless steel guiding tube (inner diameter 8 mm; length 6 m) containing two 1 m curvature radii was investigated for all pellet types. Tests were performed applying repetition rates from 2 Hz to 50 Hz and propellant gas pressures ranging from 0.1 to 0.6 MPa. For both H{sub 2} and D{sub 2}, low overall delivery efficiencies were observed at slow repetition rates, but stable efficiencies of about 90% above 10 Hz. About 10% of the mass is eroded while flying through the guiding tube. Pellets exit the guiding tube with an angular spread of less than 14°.

ORELA electron guns

International Nuclear Information System (INIS)

Christian, O.W.; Lewis, T.A.

1981-09-01

The most recent information concerning the production and performance of ORELA electron guns is presented. Included are descriptions of procedures for gun fabrication, cathode conditioning and high voltage processing. Highlights of the performance characteristics are also included

Gas Gun Model and Comparison to Experimental Performance of Pipe Guns Operating with Light Propellant Gases and Large Cryogenic Pellets

Energy Technology Data Exchange (ETDEWEB)

Reed, J. R. [University of Tennessee, Knoxville (UTK); Carmichael, J. R. [Fermi National Accelerator Laboratory (FNAL); Gebhart, T. E. [University of Florida, Gainesville; Combs, Stephen Kirk [ORNL; Baylor, Larry R. [ORNL; Rasmussen, David A. [ORNL; Meitner, Steven J. [ORNL; Lyttle, Mark S. [ORNL

2017-10-01

Injection of multiple large (~10 to 30 mm diameter) shattered pellets into ITER plasmas is presently part of the scheme planned to mitigate the deleterious effects of disruptions on the vessel components. To help in the design and optimize performance of the pellet injectors for this application, a model referred to as “the gas gun simulator” has been developed and benchmarked against experimental data. The computer code simulator is a Java program that models the gas-dynamics characteristics of a single-stage gas gun. Following a stepwise approach, the code utilizes a variety of input parameters to incrementally simulate and analyze the dynamics of the gun as the projectile is launched down the barrel. Using input data, the model can calculate gun performance based on physical characteristics, such as propellant-gas and fast-valve properties, barrel geometry, and pellet mass. Although the model is fundamentally generic, the present version is configured to accommodate cryogenic pellets composed of H2, D2, Ne, Ar, and mixtures of them and light propellant gases (H2, D2, and He). The pellets are solidified in situ in pipe guns that consist of stainless steel tubes and fast-acting valves that provide the propellant gas for pellet acceleration (to speeds ~200 to 700 m/s). The pellet speed is the key parameter in determining the response time of a shattered pellet system to a plasma disruption event. The calculated speeds from the code simulations of experiments were typically in excellent agreement with the measured values. With the gas gun simulator validated for many test shots and over a wide range of physical and operating parameters, it is a valuable tool for optimization of the injector design, including the fast valve design (orifice size and volume) for any operating pressure (~40 bar expected for the ITER application) and barrel length for any pellet size (mass, diameter, and length). Key design parameters and proposed values for the pellet injectors for

RF Design of the LCLS Gun

International Nuclear Information System (INIS)

Limborg-Deprey, C.

2010-01-01

Final dimensions for the LCLS RF gun are described. This gun, referred to as the LCLS gun, is a modified version of the UCLA/BNL/SLAC 1.6 cell S-Band RF gun (1), referred to as the prototype gun. The changes include a larger mode separation (15 MHz for the LCLS gun vs. 3.5 MHz for the prototype gun), a larger radius at the iris between the 2 cells, a reduced surface field on the curvature of the iris between the two cells, Z power coupling, increased cooling channels for operation at 120 Hz, dual rf feed, deformation tuning of the full cell, and field probes in both cells. Temporal shaping of the klystron pulse, to reduce the average power dissipated in the gun, has also been adopted. By increasing the mode separation, the amplitude of the 0-mode electric field on the cathode decreases from 10% of the peak on axis field for the prototype gun to less than 3% for the LCLS gun for the steady state fields. Beam performance is improved as shown by the PARMELA simulations. The gun should be designed to accept a future load lock system. Modifications follow the recommendations of our RF review committee (2). Files and reference documents are compiled in Section IV.

CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

Directory of Open Access Journals (Sweden)

Nediljka Gaurina-Međimurec

1994-12-01

Full Text Available During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production, pipe corrosion and expensive well repairs. Cementing temperature conditions are important because bot-tomhole circulating temperatures affect slurry thickening time, arheology, set time and compressive strength development. Knowing the actual temperature which cement encounters during placement allows the selection of proper cementing materials for a specific application. Slurry design is affected by well depth, bottom hole circulating temperature and static temperature, type or drilling fluid, slurry density, pumping time, quality of mix water, fluid loss control, flow regime, settling and free water, quality of cement, dry or liquid additives, strength development, and quality of the lab cement testing and equipment. Most Portland cements and Class J cement have shown suitable performances in geot-hermal wells. Cement system designs for geothermal wells differ from those for conventional high temperature oil and gas wells in the exclusive use of silica flour instead of silica sand, and the avoidance of fly ash as an extender. In this paper, Portland cement behaviour at high temperatures is described. Cement slurry and set cement properties are also described. Published in literature, the composition of cement slurries which were tested in geothermal conditions and which obtained required compressive strength and water permeability are listed. As a case of our practice geothermal wells Velika Ciglena-1 and Velika Ciglena-la are described.

Gun Violence Following Inpatient Psychiatric Treatment: Offense Characteristics, Sources of Guns, and Number of Victims.

Science.gov (United States)

Kivisto, Aaron J

2017-10-01

This study presents data on the relative contribution to gun violence by people with a history of inpatient psychiatric treatment and on federal efforts to deter presumptively dangerous persons from obtaining firearms, information useful for analyzing the potential public health benefits of gun policies targeting people with serious mental illness. The study also estimates the reduction in gun violence victims that would be expected if individuals with a previous psychiatric hospitalization were prohibited from purchasing firearms. Data from 838 violent gun offenders from a nationally representative sample of state prison inmates were analyzed. Those with and without a history of psychiatric hospitalization were compared on a range of offense characteristics, including relationship to the victim, number of victims, location of the offense, and source of firearms. Inmates with a history of hospitalization constituted 12% of all violent gun offenders and accounted for 13% of the sample's victims. They were less likely than those without a previous hospitalization to victimize strangers (odds ratio=.52) and were no more likely to commit gun violence in public or to have multiple victims. Among those with previous hospitalizations, 78% obtained guns from sources not subject to federal background checks. Of the total 1,041 victims of gun violence, only 3% were victimized by participants with a history of hospitalization who obtained guns from currently regulated sources. Prohibiting all individuals with a history of psychiatric hospitalization from purchasing firearms, absent expanded background checks, was estimated to reduce the number of gun violence victims by only 3%.

Unbalanced field RF electron gun

Science.gov (United States)

Hofler, Alicia

2013-11-12

A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.

From gun politics to self-defense politics: a feminist critique of the great gun debate.

Science.gov (United States)

Carlson, Jennifer D

2014-03-01

This article calls attention to a problematic binary produced by public debates surrounding gun rights and gun control-namely, that women must choose armed self-protection or no self-protection at all. I argue that both anti- and pro-gun discourses, drawing on and reproducing race and class privileges, use assumptions about women's physical inferiority to further their agendas. I highlight how both sides have used guns as the proxy for self-defense and conclude by calling for a shift in public discourse to focus on the broader question of the right to self-defense rather than the narrower question of gun rights.

A high-brightness thermionic microwave electron gun

Energy Technology Data Exchange (ETDEWEB)

Borland, Michael [Stanford Univ., CA (United States)

1991-02-01

In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun`s performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ``State-of-the-art`` microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of < 10 π • m_ec • μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 10⁹e^- per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically < 30 π • m_e • μm.

Preparation of targets using electron gun systems

International Nuclear Information System (INIS)

Maier-Komor, P.

1975-01-01

Most targets of isotopes with very low vapor pressure can only be fabricated by vacuum deposition using an electron gun system or a heavy ion sputtering system. Heavy ion sputtering is a very new technique with many unsolved problems. Therefore it seems to be easier to work with an electron gun. Different commercially available electron guns, which are all designed for the high evaporation rates used in industry, are examined for their qualification in processing small amounts of material as used in fabrication of isotope targets. Electron backscattering and the associated efficiency of the electron beam power is strongly dependent on the atomic number Z of the evaporant and the incident angle of the electron beam on the surface of the evaporant. This dependence leads also to the undesired effects to the target layers from electrons and ions. Some precautions are necessary against the effects of the electrons and ions, which are formed in the plasma directly over the beam impact point. Beam power and beam density have to be chosen to get a constant evaporation rate and a low enough condensation rate in order not to overheat the target substrates. To evaporate some metals it may be helpful to pulse the electron beam

A high-brightness thermionic microwave electron gun

International Nuclear Information System (INIS)

Borland, M.

1991-02-01

In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun's performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ''State-of-the-art'' microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of e c · μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 10 9 e - per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically e · μm

Racism, Gun Ownership and Gun Control: Biased Attitudes in US Whites May Influence Policy Decisions

OpenAIRE

O?Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

2013-01-01

OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US wh...

Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

Science.gov (United States)

Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

2010-02-01

The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter

International Nuclear Information System (INIS)

Vizir, A. V.; Tyunkov, A. V.; Shandrikov, M. V.; Oks, E. M.

2010-01-01

The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10 9 cm -3 at an operating gas pressure in the vacuum chamber of less than 2x10 -2 Pa. The device features high power efficiency, design simplicity, and compactness.

CID thermionic gun system

International Nuclear Information System (INIS)

Koontz, R.F.

1981-10-01

A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

CID thermionic gun system

International Nuclear Information System (INIS)

Koontz, R.F.

1982-01-01

A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

X-Band RF Gun Development

International Nuclear Information System (INIS)

Vlieks, A.E.

2012-01-01

In support of the MEGa-ray program at LLNL and the High Gradient research program at SLAC, a new X-band multi-cell RF gun is being developed. This gun, similar to earlier guns developed at SLAC for Compton X-ray source program, will be a standing wave structure made of 5.5 cells operating in the pi mode with copper cathode. This gun was designed following criteria used to build SLAC X-band high gradient accelerating structures. It is anticipated that this gun will operate with surface electric fields on the cathode of 200 MeV/m with low breakdown rate. RF will be coupled into the structure through a final cell with symmetric duel feeds and with a shape optimized to minimize quadrupole field components. In addition, geometry changes to the original gun, operated with Compton X-ray source, will include a wider RF mode separation, reduced surface electric and magnetic fields.

Nail gun injuries to the head with minimal neurological consequences: a case series.

Science.gov (United States)

Makoshi, Ziyad; AlKherayf, Fahad; Da Silva, Vasco; Lesiuk, Howard

2016-03-16

An estimated 3700 individuals are seen annually in US emergency departments for nail gun-related injuries. Approximately 45 cases have been reported in the literature concerning nail gun injuries penetrating the cranium. These cases pose a challenge for the neurosurgeon because of the uniqueness of each case, the dynamics of high pressure nail gun injuries, and the surgical planning to remove the foreign body without further vascular injury or uncontrolled intracranial hemorrhage. Here we present four cases of penetrating nail gun injuries with variable presentations. Case 1 is of a 33-year-old white man who sustained 10 nail gunshot injuries to his head. Case 2 is of a 51-year-old white man who sustained bi-temporal nail gun injuries to his head. Cases 3 and 4 are of two white men aged 22 years and 49 years with a single nail gun injury to the head. In the context of these individual cases and a review of similar cases in the literature we present surgical approaches and considerations in the management of nail gun injuries to the cranium. Case 1 presented with cranial nerve deficits, Case 2 required intubation for low Glasgow Coma Scale, while Cases 3 and 4 were neurologically intact on presentation. Three patients underwent angiography for assessment of vascular injury and all patients underwent surgical removal of foreign objects using a vice-grip. No neurological deficits were found in these patients on follow-up. Nail gun injuries can present with variable clinical status; mortality and morbidity is low for surgically managed isolated nail gun-related injuries to the head. The current case series describes the surgical use of a vice-grip for a good grip of the nail head and controlled extraction, and these patients appear to have a good postoperative prognosis with minimal neurological deficits postoperatively and on follow-up.

Role of Substrate on Quartz Cementation in Quartz Aggregates

Science.gov (United States)

Farver, J. R.; Winslow, D.; Onasch, C.

2010-12-01

Quartz cementation in quartz aggregates has been experimentally investigated. The starting material was disaggregated detrital quartz grains from the well-sorted, mature St. Peter Sandstone. The ‘as-is’ grains have patches of iron oxide coatings and some have euhedral overgrowths that contain iron oxide dust rims. In addition a set of experiments was run using grains that were cleaned by soaking in sodium hydrosulfite and sodium bisulfate solutions to remove exposed iron oxide coatings. Experimental charges consisted of amorphous silica powder (≈30 mg) to provide a source of silica for the quartz cement, AlCl3 powder (≈3 mg) to provide a tracer for Cathodoluminescence (CL) identification of cement formed during the experiment, 25 wt% NaCl brine solution (≈25 mg) to increase the silica solubility and to better mimic oil field brines, and the natural quartz grains (100-130 mg). The charges were weld-sealed in Au capsules and run in cold-seal pressure vessels at 250°C to 450°C at 150 MPa confining pressure for up to 8 weeks. After the experiments, the samples were vacuum impregnated with a low viscosity epoxy containing a blue dye. After curing, the sample charge was sawn in half along its long axis and one half was polished (to 1 micron diamond paste) for analysis. The nature and amount of quartz cement in the samples were determined by a combination of CL, light microscopy, and scanning electron microscopy. Photomosaics of the samples were created and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement formed during the experiment was easily recognized from the quartz grains (and previous overgrowths) by the difference in luminescence. The results indicate the amorphous silica powder provides a ready source for silica for quartz cementation due to its greater solubility than the quartz. The cementation rates are rapid (>14% cement formed in 2 weeks at 450°C and >7% in 8 weeks at 250°C). Compared to

Preventing gun injuries in children.

Science.gov (United States)

Crossen, Eric J; Lewis, Brenna; Hoffman, Benjamin D

2015-02-01

Firearms are involved in the injury and death of a large number of children each year from both intentional and unintentional causes. Gun ownership in homes with children is common, and pediatricians should incorporate evidence-based means to discuss firearms and protect children from gun-related injuries and violence. Safe storage of guns, including unloaded guns locked and stored separately from ammunition, can decrease risks to children, and effective tools are available that pediatricians can use in clinical settings to help decrease children's access to firearms. Furthermore, several community-based interventions led by pediatricians have effectively reduced firearm-related injury risks to children. Educational programs that focus on children's behavior around guns have not proven effective. © American Academy of Pediatrics, 2015. All rights reserved.

Gun violence trends in movies.

Science.gov (United States)

Bushman, Brad J; Jamieson, Patrick E; Weitz, Ilana; Romer, Daniel

2013-12-01

Many scientific studies have shown that the mere presence of guns can increase aggression, an effect dubbed the "weapons effect." The current research examines a potential source of the weapons effect: guns depicted in top-selling films. Trained coders identified the presence of violence in each 5-minute film segment for one-half of the top 30 films since 1950 and the presence of guns in violent segments since 1985, the first full year the PG-13 rating (age 13+) was used. PG-13-rated films are among the top-selling films and are especially attractive to youth. Results found that violence in films has more than doubled since 1950, and gun violence in PG-13-rated films has more than tripled since 1985. When the PG-13 rating was introduced, these films contained about as much gun violence as G (general audiences) and PG (parental guidance suggested for young children) films. Since 2009, PG-13-rated films have contained as much or more violence as R-rated films (age 17+) films. Even if youth do not use guns, these findings suggest that they are exposed to increasing gun violence in top-selling films. By including guns in violent scenes, film producers may be strengthening the weapons effect and providing youth with scripts for using guns. These findings are concerning because many scientific studies have shown that violent films can increase aggression. Violent films are also now easily accessible to youth (e.g., on the Internet and cable). This research suggests that the presence of weapons in films might amplify the effects of violent films on aggression.

Effect of charge exchange on ion guns and an application to inertial- electrostatic confinement devices

International Nuclear Information System (INIS)

Baxter, D.C.; Stuart, G.W.

1982-01-01

In 1967, R. L. Hirsch [J. Appl. Phys. 38, 4522 (1967)] reported neutron production rates of 10 10 neutrons per second from an electrostatic inertial confinement device. The device consisted of six ion guns injecting deuterium or a mixture of deuterium and tritium ions into an evacuated cathode chamber at 30--150 keV. No previous theoretical model for this experiment has adequately explained the observed neutron fluxes. A new model that includes the effects of charge exchange and ionization in the ion guns is analyzed. This model predicts three main features of the observed neutron flux: Neutron output proportional to gun current, neutron production localized at the center of the evacuated chamber, and neutron production decreasing with increasing neutral background gas density. Previous analysis modelled the ion guns as being monoenergetic. In this study, the ion gun output is modelled as a mixture of ions and fast neutrals with energies ranging from zero to the maximum gun energy. Using this theoretical model, a survey of the possible operating parameters indicates that the device was probably operated at or near the most efficient combined values of voltage and background pressure. Applications of the theory to other devices are discussed

Low emittance thermionic electron guns

International Nuclear Information System (INIS)

Herrmannsfeldt, W.B.

1989-01-01

The author discusses self-field effects and external field effects for electron guns. He also discusses designs of electron guns and their uses in electron cooling systems and as an injector for electrostatic free electron lasers. He closes by looking at electron guns for linear accelerators. 20 references, 3 figures

Guns at College.

Science.gov (United States)

Miller, Matthew; Hemenway, David; Wechsler, Henry

1999-01-01

Surveyed undergraduate students nationwide concerning firearm possession. About 3.5% possessed working firearms. Students with guns were more likely to be male, White, or Native American; binge drink; live off-campus; and live with a spouse or significant other. Students with guns were more likely to engage in activities that put themselves and…

Relationship between licensing, registration, and other gun sales laws and the source state of crime guns.

Science.gov (United States)

Webster, D W; Vernick, J S; Hepburn, L M

2001-09-01

To determine the association between licensing and registration of firearm sales and an indicator of gun availability to criminals. Tracing data on all crime guns recovered in 25 cities in the United States were used to estimate the relationship between state gun law categories and the proportion of crime guns first sold by in-state gun dealers. In cities located in states with both mandatory registration and licensing systems (five cities), a mean of 33.7% of crime guns were first sold by in-state gun dealers, compared with 72.7% in cities that had either registration or licensing but not both (seven cities), and 84.2% in cities without registration or licensing (13 cites). Little of the difference between cities with both licensing and registration and cities with neither licensing nor registration was explained by potential confounders. The share of the population near a city that resides in a neighboring state without licensing or registration laws was negatively associated with the outcome. States with registration and licensing systems appear to do a better job than other states of keeping guns initially sold within the state from being recovered in crimes. Proximity to states without these laws, however, may limit their impact.

Results of the AFWL deflagration gun experiments

International Nuclear Information System (INIS)

Hackett, K.E.; Baker, W.L.; Beason, J.D.

1987-01-01

The snowplow and deflagration modes of coaxial plasma gun operation have been experimentally investigated and computationally simulated at the Air Force Weapons Laboratory. The snowplow mode occurs when the gun is prefilled to a uniform gas density. The initial breakdown forms near the insulator at the gun breech. It heats the gas and creates a shock wave that travels down the gun, ionizing gas and producing a thin current sheath that travels just behind the shock front. The shock front piles up the gas in front of itself as it moves down the gun - hence the name ''snowplow''. Deflagration occurs when gas is injected into an evacuated gun so that the initial breakdown forms as the gas fills the gun. The ionized gas is accelerated into the vacuum region carrying current and magnetic field with it. A quasi-stationary diffuse discharge develops. Gas still entering the gun is processed through the deflagrating discharge and accelerated out the gun muzzle

RF guns: a review

International Nuclear Information System (INIS)

Travier, C.

1990-06-01

Free Electron Lasers and future linear colliders require very bright electron beams. Conventional injectors made of DC guns and RF bunchers have intrinsic limitations. The recently proposed RF guns have already proven their capability to produce bright beams. The necessary effort to improve further these performances and to gain reliability is now undertaken by many laboratories. More than twenty RF gun projects both thermionic and laser-driven are reviewed. Their specific characteristics are outlined and their nominal performances are given

THE IMPROVEMENT AND APPLICATION OF EI-GUN (ELECTRICAL INSEMINATION GUN FOR ARTIFICIAL INSEMINATION (AI USING GOAT FRESH SEMEN

Directory of Open Access Journals (Sweden)

Mirsa Ita Dewi

2017-03-01

Full Text Available Electrical Insemination Gun (EI-GUN was a tool for Artificial Insemination (AI using fresh semen with an electric control system. The research objective was to produced EI-GUN for AI using fresh semen on small ruminants (goat. The research was conducted from March to June 2015. The process of EI-GUN creation implemented in Design and Prototype Laboratory and Aero Modeling Research Laboratory at Engineering Faculty, University of Brawijaya (UB. Testing tools EI-GUN on goat was conducted in the Sumber Sekar Laboratory, Animal Husbandry Faculty, UB.  The methods of research were literature study, tool specification determination, designing EI-GUN, running test, semen evaluation passed EI-GUN and application on Goat. EI-GUN has seven important parts, which supports each other in this operating system. Those parts consist of stylet, servo, system controlled, insemination pump, connecting rod, battery, and holder. EI-GUN work system sucked the semen into insemination pump as much as 5 ml, and release the semen 0.25 ml appropriate standard of AI. It was applicable for 20 times AI. The results showed that the cell motility of spermatozoa ≥ 70% were still in ranging of Indonesian National Standard (SNI.   Keywords: artificial insemination, EI-GUN, fresh semen.

Slurry circulation after cement compression operations; Circulacao de pasta apos operacoes de compressao de cimento

Energy Technology Data Exchange (ETDEWEB)

Costa, Clavio Roberto S [PETROBRAS, BA (Brazil). Regiao de Producao da Bahia. Divisao Regional de Complementacao

1994-07-01

In the traditional low pressure cement compression method, after pressure stabilization we wait for the setting and remove the hardened cement with a rock bit. The method described here suggests that following pressure stabilization, the slurry must be removed from the casing with reverse circulation, thus excluding the whole process of cutting hardened cement, optimizing rig time and equipment wear, and anticipating oil production. This work describes this experience in Reconcavo basin, Potiguar basin, and Campos basin, production regions of PETROBRAS, and suggests slurry parameters and a methodology to employ the method. (author)

Understanding and Predicting Gun Barrel Erosion

National Research Council Canada - National Science Library

Johnston, Ian A

2005-01-01

The Australian Defence Force will soon have to contend with gun barrel erosion issues arising from the use of new low-vulnerability gun propellants, the acquisition of new ammunition and gun systems...

Two-dimensional computational modeling of high-speed transient flow in gun tunnel

Science.gov (United States)

Mohsen, A. M.; Yusoff, M. Z.; Hasini, H.; Al-Falahi, A.

2018-03-01

In this work, an axisymmetric numerical model was developed to investigate the transient flow inside a 7-meter-long free piston gun tunnel. The numerical solution of the gun tunnel was carried out using the commercial solver Fluent. The governing equations of mass, momentum, and energy were discretized using the finite volume method. The dynamic zone of the piston was modeled as a rigid body, and its motion was coupled with the hydrodynamic forces from the flow solution based on the six-degree-of-freedom solver. A comparison of the numerical data with the theoretical calculations and experimental measurements of a ground-based gun tunnel facility showed good agreement. The effects of parameters such as working gases and initial pressure ratio on the test conditions in the facility were examined. The pressure ratio ranged from 10 to 50, and gas combinations of air-air, helium-air, air-nitrogen, and air-CO2 were used. The results showed that steady nozzle reservoir conditions can be maintained for a longer duration when the initial conditions across the diaphragm are adjusted. It was also found that the gas combination of helium-air yielded the highest shock wave strength and speed, but a longer test time was achieved in the test section when using the CO2 test gas.

Cementation of the solid radioactive waste with polymer-cement solutions using the method of impregnation

International Nuclear Information System (INIS)

Gorbunova, O.

2015-01-01

Cementation of solid radioactive waste (SRW), i.e. inclusion of solid radioactive waste into cement matrix without cavities - is one of the main technological processes used for conditioning low and intermediate level radioactive waste. At FSUE 'Radon' the industrialized method of impregnation has been developed and since 2003 has been using for cementation of solid radioactive waste. The technology is that the polymer-cement solution, having high penetrating properties, is supplied under pressure through a tube to the bottom of the container in which solid radioactive waste has preliminarily been placed. The polymer-cement solution is evenly moving upwards through the channels between the particles of solid radioactive waste, fills the voids in the bulk volume of the waste and hardens, forming a cement compound, the amount of which is equal to the original volume. The aim of the investigation was a selection of a cement solution suitable for SRW impregnation (including fine particles) without solution depletion and bottom layers stuffing. It has been chosen a polymer: PHMG (polyhexamethylene-guanidine), which is a stabilizing and water-retaining component of the cement solution. The experiments confirm that the polymer increases the permeability of the cement solution by a 2-2.5 factor, the viscosity by a 1.2 factor, the stability of the consistency by a 1.5-1.7 factor, and extends the operating range of the W/C ratio to 0.5-1.1. So it is possible to penetrate a volume of SRW bigger by a 1.5-2.0 factor. It has been proved, that PHMG polymer increases strength and frost-resistance of the final compounds by a 1.8-2.7 factor, and contributes to fast strength development at the beginning of hardening and it decreases Cs-137 leashing rate by a 1.5-2 factor

Optimal control of gun recoil in direct fire using magnetorheological absorbers

International Nuclear Information System (INIS)

Singh, Harinder J; Wereley, Norman M

2014-01-01

Optimal control of a gun recoil absorber is investigated for minimizing recoil loads and maximizing rate of fire. A multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper. The damper forces are predicted by evaluating pressure drops using a nonlinear Bingham-plastic model. The optimization methodology provides multiple optimal design configurations with a trade-off between recoil load minimization and increased rate of fire. The configurations with low or high recoil loads imply low or high rate of fire, respectively. The gun recoil absorber performance is also analyzed for perturbations in the firing forces. The adaptive control of the MR damper for varying gun firing forces provides a smooth operation by returning the recoil mass to its battery position (ready to reload and fire) without incurring an end-stop impact. Furthermore, constant load transmissions are observed with respect to the recoil stroke by implementing optimal control during the simulated firing events. (paper)

Optimal control of gun recoil in direct fire using magnetorheological absorbers

Science.gov (United States)

Singh, Harinder J.; Wereley, Norman M.

2014-05-01

Optimal control of a gun recoil absorber is investigated for minimizing recoil loads and maximizing rate of fire. A multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper. The damper forces are predicted by evaluating pressure drops using a nonlinear Bingham-plastic model. The optimization methodology provides multiple optimal design configurations with a trade-off between recoil load minimization and increased rate of fire. The configurations with low or high recoil loads imply low or high rate of fire, respectively. The gun recoil absorber performance is also analyzed for perturbations in the firing forces. The adaptive control of the MR damper for varying gun firing forces provides a smooth operation by returning the recoil mass to its battery position (ready to reload and fire) without incurring an end-stop impact. Furthermore, constant load transmissions are observed with respect to the recoil stroke by implementing optimal control during the simulated firing events.

Electron gun for SSRF

International Nuclear Information System (INIS)

Sheng Shugang; Lin Guoqiang; Gu Qiang; Li Deming

2003-01-01

A 100 kV triode-electron-gun has been designed and manufactured for the Linac of Shanghai Synchrotron Radiation Facility (SSRF). In this paper the performance of the gun and some key components are described

Automatic targeting of plasma spray gun

Science.gov (United States)

Abbatiello, Leonard A.; Neal, Richard E.

1978-01-01

A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun.

Automatic targeting of plasma spray gun

International Nuclear Information System (INIS)

Abbatiello, L.A.; Neal, R.E.

1978-01-01

A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is described. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun

Electron gun for technological linear accelerator

International Nuclear Information System (INIS)

Khodak, I.V.; Kushnir, V.A.; Mirochenko, V.V.; Stepin, D.L.; Zavada, L.M.

2000-01-01

The work is purposed to the design of diode electron gun for powerful technologic electron linac and to experimental investigations of the beam parameters at the gun exit.The gun feature is the quick cathode replacement.This is very impotent for operating of the accelerator.The gun optics and beam parameters were calculated using the EGUN code.Beam parameters were investigated as at the special test stand so as component of the linac injector.The gun produces the beam current of 2 A at the anode voltage 25 kV.Measured beam parameters correspond to calculated results

Are "goods for guns" good for the community? An update of a community gun buyback program.

Science.gov (United States)

Green, Jonathan; Damle, Rachelle N; Kasper, Rebecca E; Violano, Pina; Manno, Mariann; Nazarey, Pradeep P; Aidlen, Jeremy T; Hirsh, Michael P

2017-08-01

Gun violence remains a leading cause of death in the United States. Community gun buyback programs provide an opportunity to dispose of extraneous firearms. The purpose of this study was to understand the demographics, motivation, child access to firearms, and household mental illness of buyback participants in hopes of improving the program's effectiveness. A 2015 Injury Free Coalition for Kids gun buyback program which collaborated with local police departments was studied. We administered a 23-item questionnaire survey to gun buyback participants assessing demographic characteristics, motivation for relinquishing firearms, child firearm accessibility, and mental illness/domestic violence history. A total of 186 individuals from Central/Western Massachusetts turned in 339 weapons. Participants received between US $25 and US $75 in gift cards dependent on what type of gun was turned in, with an average cost of $41/gun. A total of 109 (59%) participants completed the survey. Respondents were mostly white (99%), men (90%) and first-time participants in the program (85.2%). Among survey respondents, 54% turned in firearms "for safety reasons." Respondents reported no longer needing/wanting their weapons (47%) and approximately one in eight participants were concerned the firearm(s) were accessible to children. Most respondents (87%) felt the program encouraged neighborhood awareness of firearm safety. Three of every five participants reported that guns still remained in their homes; additionally, 21% where children could potentially access them and 14% with a history of mental illness/suicide/domestic violence in the home. Gun buybacks can provide a low-cost means of removing unwanted firearms from the community. Most participants felt their homes were safer after turning in the firearm(s). In homes still possessing guns, emphasis on secure gun storage should continue, increasing the safety of children and families. The results of this survey also provided new

The ALS Gun Electronics system

International Nuclear Information System (INIS)

Lo, C.C.

1993-05-01

The ALS Gun Electronics system has been designed to accommodate gun with a custom made socket and high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

The ALS gun electronics system

International Nuclear Information System (INIS)

Lo, C.C.

1993-01-01

The ALS Gun Electronics system has been designed to accommodate the gun with a custom made socket and a high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

Science.gov (United States)

Thom, Karlheinz; Norwood, Joseph, Jr.

1961-01-01

The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

Interactions between cement grouts and sulphate bearing ground water

International Nuclear Information System (INIS)

Walton, P.L.; Duerden, S.L.; Atkins, K.M.; Majumdar, A.J.

1989-01-01

The physical, chemical and mineralogical properties of mixtures of Ordinary Portland cement and blastfurnace slag or pulverized fuel ash, exposed to a sulphate-bearing ground water at different temperatures and pressures, were investigated in order to assess the long term durability of cements for encapsulating radioactive waste and backfilling a repository. The effect of the ground water on the chemical and mineralogical characteristics of the cements is minimal. Calcite and C-S-H are present in all the samples and are durable throughout the test. Dimensional changes in the cements during setting and curing may cause weaknesses in the materials which may increase the effects of a percolating ground water. (author)

Glue Guns: Aiming for Safety

Science.gov (United States)

Roy, Ken

2010-01-01

While glue guns are very useful, there are safety issues. Regardless of the temperature setting, glue guns can burn skin. The teacher should demonstrate and supervise the use of glue guns and have a plan should a student get burned. There should be an initial first aid protocol in place, followed by a visit to the school nurse. An accident report…

"Is there a gun in the home?" Assessing the risks of gun ownership in older adults.

Science.gov (United States)

Pinholt, Ellen M; Mitchell, Joshua D; Butler, Jane H; Kumar, Harjinder

2014-06-01

An important ethical and safety concern that geriatricians, primary care providers, and home health professionals need to address is gun ownership by elderly adults. Those aged 65 and older now have the highest rate of gun ownership in America, and they also have a high prevalence of depression and suicide. Dementia can add additional layers of risk. Even older gun owners who are otherwise intellectually intact may benefit from information about gun safety with the increasing numbers of children being cared for by grandparents. Health professionals should ask patients, "Is there a gun in the home?" in the clinic and during home visits. Healthcare professionals must have knowledge and skills to address safe gun ownership in elderly adults. The 5 L's (Locked, Loaded, Little children, feeling Low, Learned owner) will assist professionals in addressing all aspects of safe ownership. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

Influence of bone density on the cement fixation of femoral hip resurfacing components.

Science.gov (United States)

Bitsch, Rudi G; Jäger, Sebastian; Lürssen, Marcus; Loidolt, Travis; Schmalzried, Thomas P; Clarius, Michael

2010-08-01

In clinical outcome studies, small component sizes, female gender, femoral shape, focal bone defects, bad bone quality, and biomechanics have been associated with failures of resurfacing arthroplasties. We used a well-established experimental setup and human bone specimens to analyze the effects of bone density on cement fixation of femoral hip resurfacing components. Thirty-one fresh frozen femora were prepared for resurfacing using the original instruments. ASR resurfacing prostheses were implanted after dual-energy X-ray densitometer scans. Real-time measurements of pressure and temperature during implantation, analyses of cement penetration, and measurements of micro motions under torque application were performed. The associations of bone density and measurement data were examined calculating regression lines and multiple correlation coefficients; acceptability was tested with ANOVA. We found significant relations between bone density and micro motion, cement penetration, cement mantle thickness, cement pressure, and interface temperature. Mean bone density of the femora was 0.82 +/- 0.13 g/cm(2), t-score was -0.7 +/- 1.0, and mean micro motion between bone and femoral resurfacing component was 17.5 +/- 9.1 microm/Nm. The regression line between bone density and micro motion was equal to -56.7 x bone density + 63.8, R = 0.815 (p density scans are most helpful for patient selection in hip resurfacing, and a better bone quality leads to higher initial component stability. A sophisticated cementing technique is recommended to avoid vigorous impaction and incomplete seating, since increasing bone density also results in higher cement pressures, lower cement penetration, lower interface temperatures, and thicker cement mantles. Copyright 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Gun buyback programs: a venue to eliminate unwanted guns in the community.

Science.gov (United States)

Violano, Pina; Driscoll, Cassandra; Chaudhary, Neil K; Schuster, Kevin M; Davis, Kimberly A; Borer, Esther; Winters, Jane K; Hirsh, Michael P

2014-09-01

The United States has a high rate of death due to firearms, and gun buyback programs may mitigate these high death rates. Understanding the demographics, motivation, and geographic region of participants may improve program efficacy. Three Injury Free Coalition for Kids gun buyback programs, in collaboration with the local police, were studied: Phoenix, Arizona; Worcester, Massachusetts; and New Haven, Connecticut. Participants were defined as those who relinquished a firearm. A self-administered, anonymous, paper survey elicited information from participants regarding demographic data, formal training on the use of the firearm, how the firearm was acquired, potential child access, knowledge of others injured by a firearm, whether the firearm was stored unlocked, factors motivating the surrender of the firearm, and other factors. Survey results were entered into a composite database and analyzed for differences in location, race, sex, and other factors. Participants (n = 301) were predominantly male (73.5%), white (80.9%), and older than 55 years (59.0%). They lived an average of 19.0 miles from the event by zip codes and had an average median household income of $65,731. More than half (54.5%) did not purchase the firearm, acquiring it through inheritance, gift, or random find. Most (74.8%) had previous firearms training and were relinquishing for safety reasons (68.3%). Those relinquishing firearms for safety reasons were less likely to have purchased the firearm (odds ratio [OR], 2.46, p gun lock (OR, 0.15; p gun-wielding criminal acts were burglarized from the home of legal gun owners that had failed to secure them properly. The gun buyback program is solely one prong of a multipronged approach in reducing firearm-based interpersonal violence. Additional research is necessary to determine effective methods to target individuals who would have the greatest impact on gun violence if they relinquished their weapons. Through the forging of relationships and

Zinc phosphate as a definitive cement for implant-supported crowns and fixed dentures

Directory of Open Access Journals (Sweden)

Flanagan D

2017-11-01

Full Text Available Dennis Flanagan Private Practice, Willimantic, CT, USA Abstract: Implant-supported dental prostheses can be retained by a screw or cement. Implant-supported fixed partial dentures have a passive fit. A passive fit means there is an internal gap between the abutment surface and the intaglio of the retainer to insure that there is no lateral pressure on the supporting implants or friction upon seating of the prosthesis. This gap is filled with cement for retention of the prosthesis. Any lateral pressure may cause marginal bone loss or periimplantitis. Also, there is usually a microscopic gap at the margin of a crown retainer that exposes the cement to oral fluids. The solubility of zinc phosphate (ZOP cement is a definite liability due to the risk for cement dissolution. In fixed prostheses, the dissolution of the cement of one or more retainers would cause a transfer of the occlusal load to the retained unit(s. The resulting rotation and lifting of the cement-retained implants from occlusal and parafunctional loads could cause loss of osseointegration of the abutment-retained implant(s. ZOP cement may not be indicated for implant-supported fixed partial dentures or splints. Cement dissolution in single unit probably only involves re-cementation, if the patient does not swallow or aspirate the crown. Keywords: passive fit, retention, film thickness, fixed, marginal gap 

A 20 keV electron gun system for the electron irradiation experiments

International Nuclear Information System (INIS)

Mahapatra, S.K.; Dhole, S.D.; Bhoraskar, V.N.

2005-01-01

An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 μA. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure ∼10 -7 mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours

A 20 keV electron gun system for the electron irradiation experiments

Energy Technology Data Exchange (ETDEWEB)

Mahapatra, S.K. [Department of Physics, University of Pune, Pune 411007 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 411007 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411007 (India)]. E-mail: vnb@physics.unipune.ernet.in

2005-01-01

An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 {mu}A. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure {approx}10{sup -7} mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours.

Instantaneous current and field structure of a gun-driven spheromak for two gun polarities

International Nuclear Information System (INIS)

Woodruff, S; Nagata, M

2002-01-01

The instantaneous plasma structure of the SPHEX spheromak is determined here by numerically processing data from insertable Rogowski and magnetic field probes. Data is presented and compared for two modes of gun operation: with the central electrode biased positively and negatively. It is found that while the mean-, or even instantaneous-, field structure would give the impression of a roughly axisymmetric spheromak, the instantaneous current structure does not. Hundred per cent variations in J measured at the magnetic axis can be explained by the rotation of a current filament that has a width equal to half of the radius of the flux-conserving first wall. In positive gun operation, current leaves the filament in the confinement region leading to high wall current there. In negative gun operation, wall current remains low as all injected current returns to the gun through the plasma. The plasma, in either instance, is strongly asymmetric. We discuss evidence for the existence of the current filament in other gun-driven spheromaks and coaxial plasma thrusters

Heavy duty plasma spray gun

International Nuclear Information System (INIS)

Irons, G.C.; Klein, J.F.; Lander, R.D.; Thompson, H.C.; Trapani, R.D.

1984-01-01

A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith

LCLS Gun Solenoid Design Considerations

International Nuclear Information System (INIS)

Schmerge, John

2010-01-01

The LCLS photocathode rf gun requires a solenoid immediately downstream for proper emittance compensation. Such a gun and solenoid have been operational at the SSRL Gun Test Facility (GTF) for over eight years. Based on magnetic measurements and operational experience with the GTF gun solenoid multiple modifications are suggested for the LCLS gun solenoid. The modifications include adding dipole and quadrupole correctors inside the solenoid, increasing the bore to accommodate the correctors, decreasing the mirror plate thickness to allow the solenoid to move closer to the cathode, cutouts in the mirror plate to allow greater optical clearance with grazing incidence cathode illumination, utilizing pancake coil mirror images to compensate the first and second integrals of the transverse fields and incorporating a bipolar power supply to allow for proper magnet standardization and quick polarity changes. This paper describes all these modifications plus the magnetic measurements and operational experience leading to the suggested modifications.

77 FR 37834 - Revocation of Certain Requirements Pertaining to Caps Intended for Use With Toy Guns and Toy Guns...

Science.gov (United States)

2012-06-25

... Certain Requirements Pertaining to Caps Intended for Use With Toy Guns and Toy Guns Not Intended for Use With Caps AGENCY: Consumer Product Safety Commission. ACTION: Notice of proposed rulemaking. SUMMARY... compliance than our existing regulations pertaining to caps intended for use with toy guns and toy guns not...

Development of an Improved Cement for Geothermal Wells

Energy Technology Data Exchange (ETDEWEB)

Trabits, George [Trabits Group, LLC, Wasilla, AK (United States)

2015-04-20

After an oil, gas, or geothermal production well has been drilled, the well must be stabilized with a casing (sections of steel pipe that are joined together) in order to prevent the walls of the well from collapsing. The gap between the casing and the walls of the well is filled with cement, which locks the casing into place. The casing and cementing of geothermal wells is complicated by the harsh conditions of high temperature, high pressure, and a chemical environment (brines with high concentrations of carbon dioxide and sulfuric acid) that degrades conventional Portland cement. During the 1990s and early 2000s, the U.S. Department of Energy’s Geothermal Technologies Office (GTO) provided support for the development of fly-ash-modified calcium aluminate phosphate (CaP) cement, which offers improved resistance to degradation compared with conventional cement. However, the use of CaP cements involves some operational constraints that can increase the cost and complexity of well cementing. In some cases, CaP cements are incompatible with chemical additives that are commonly used to adjust cement setting time. Care must also be taken to ensure that CaP cements do not become contaminated with leftover conventional cement in pumping equipment used in conventional well cementing. With assistance from GTO, Trabits Group, LLC has developed a zeolite-containing cement that performs well in harsh geothermal conditions (thermal stability at temperatures of up to 300°C and resistance to carbonation) and is easy to use (can be easily adjusted with additives and eliminates the need to “sterilize” pumping equipment as with CaP cements). This combination of properties reduces the complexity/cost of well cementing, which will help enable the widespread development of geothermal energy in the United States.

Theoretical investigation of a travelling-wave rf gun

International Nuclear Information System (INIS)

Gao, J.

1991-12-01

A travelling-wave type rf gun (TW gun) is investigated theoretically. Analytical formulae concerning energy gain, energy spread, and transverse emittance are derived. After showing the corresponding formulae for the standing-wave rf gun (SW gun), comparisons are made between the two types of rf gun. Finally, some numerical results are calculated to demonstrate further the behaviours of the TW gun, and to compare with those from analytical formulae. (author) 11 refs.; 27 figs

One nanosecond pulsed electron gun systems

International Nuclear Information System (INIS)

Koontz, R.F.

1979-02-01

At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun

Design and development of a pierce electron gun

International Nuclear Information System (INIS)

Bhattacharjee, D.; Tiwari, R.; Nayak, B.; Tillu, A.R.; Jayaprakash, D.; Mishra, R.L.; Mittal, K.C.; Chakravarthy, D.P.; Gantayet, L.M.

2011-01-01

An electron gun is designed and developed using the Pierce configuration for the focusing electrode. Simulations were carried out using CST Particle Studio. The Gun is a thermionic type electron gun with indirect heating of the LaB6 cathode. The gun is capable of delivering a beam current of 500 mA at 50 kV with a beam size of less than 3.5 mm. It was tested on the gun test bench. This paper presents the gun design, particle simulations study, testing of the gun on test bench and integration with the ECIL 9 MeV linac. (author)

Electron gun for the Fel Clio

International Nuclear Information System (INIS)

Chaput, R.

1990-01-01

A triode electron gun has been developed and manufactured at LURE (Laboratoire pour l'Utilisation du Rayonnement Electromagnetique) and LAL (Laboratoire de l'Accelerateur Lineaire) for the free electron laser CLIO 1 (Collaboration pour un laser a electrons libres dans l'infrarouge a Orsay) now under construction: this gun involves a grid-cathode assembly manufactured by EIMAC, currently used in the SLAC gun family. For the FEL requirements, the gun must be able to yield a train of short pulses at accuracy frequency or a continuous pulse. Driving together the cathode and the grid the gun produces a continous beam of 12 μs or a pulsed beam of very short pulse of 1 ns at 250 MHz, 125 MHz, 62.5 MHz or 31.25 MHz. The performances of the gun has been tested on a testing bench. A peak current of 1 Amp. for 1 ns width at any frequencies was achieved at an injection voltage of 90 kV

Magnetized Target Fusion Propulsion: Plasma Injectors for MTF Guns

Science.gov (United States)

Griffin, Steven T.

2003-01-01

To achieve increased payload size and decreased trip time for interplanetary travel, a low mass, high specific impulse, high thrust propulsion system is required. This suggests the need for research into fusion as a source of power and high temperature plasma. The plasma would be deflected by magnetic fields to provide thrust. Magnetized Target Fusion (MTF) research consists of several related investigations into these topics. These include the orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the gun as it relates to plasma initiation and repeatability are under investigation. One of the items under development is the plasma injector. This is a surface breakdown driven plasma generator designed to function at very low pressures. The performance, operating conditions and limitations of these injectors need to be determined.

Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics

Science.gov (United States)

Osorio, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

2012-01-01

Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or sandblasted alumina showed the most stable interfaces. CAL experimented spontaneous debonding in all tested groups. Key words:CAD/CAM ceramic, alumina, zirconia, resin cement, surface pre-treatment, sandblasting, silica-coating, chemical aging, bond degradation, microtensile bond strength. PMID:22322517

Gas gun dynamics

International Nuclear Information System (INIS)

Denny, Mark

2013-01-01

The mechanics and thermodynamics of one- and two-stage gas guns are developed. Very high projectile muzzle speed can be obtained by the two-stage version. The physics of simple gas guns, such as air rifles, is accessible to undergraduates and the same level of presentation is used here to understand more complex designs. Numerical solutions to the equations of motion are shown, along with insightful analytic approximations. (paper)

Alignment Fixtures For Vacuum-Plasma-Spray Gun

Science.gov (United States)

Woodford, William H.; Mckechnie, Timothy N.; Power, Christopher A.; Daniel, Ronald L., Jr.

1993-01-01

Fixtures for alignment of vacuum-plasma-spray guns built. Each fixture designed to fit specific gun and holds small, battery-powered laser on centerline of gun. Laser beam projects small red dot where centerline intersects surface of workpiece to be sprayed. After laser beam positioned on surface of workpiece, fixture removed from gun and spraying proceeds.

Pressure dependence of morphology and phase composition of SiC films deposited by microwave plasma chemical vapor deposition on cemented carbide substrates

Energy Technology Data Exchange (ETDEWEB)

Yu Shengwang, E-mail: bkdysw@yahoo.cn; Fan Pengwei; Tang Weizhong; Li Xiaojing; Hu Haolin; Hei Hongjun; Zhang Sikai; Lu Fanxiu

2011-11-01

SiC films were deposited on cemented carbide substrates by employing microwave plasma chemical vapor deposition method using tetramethylsilane (Si(CH{sub 3}){sub 4}) diluted in H{sub 2} as the precursor. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and scratching technique were used to characterize morphology, composition, phases present and adhesion of the films. Experimental results show that the deposition pressure has great influence on morphologies and phase composition of the films. In sequence, SiC films with a cauliflower-like microstructure, granular films with terrace-featured SiC particles coexisting with Co{sub 2}Si compound and clusters of nanometer SiC nanoplatelets appear as a function of the deposition pressure. In terms of plasma density and substrate temperature, this sequential appearance of microstructures of SiC films was explained. Adhesion tests showed that among the three types of films studied, the films with the terrace-featured SiC particles have relatively higher adhesion. Such knowledge will be of importance when the SiC films are used as interlayer between diamond films and cemented carbide substrates.

Pressure dependence of morphology and phase composition of SiC films deposited by microwave plasma chemical vapor deposition on cemented carbide substrates

International Nuclear Information System (INIS)

Yu Shengwang; Fan Pengwei; Tang Weizhong; Li Xiaojing; Hu Haolin; Hei Hongjun; Zhang Sikai; Lu Fanxiu

2011-01-01

SiC films were deposited on cemented carbide substrates by employing microwave plasma chemical vapor deposition method using tetramethylsilane (Si(CH 3 ) 4 ) diluted in H 2 as the precursor. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and scratching technique were used to characterize morphology, composition, phases present and adhesion of the films. Experimental results show that the deposition pressure has great influence on morphologies and phase composition of the films. In sequence, SiC films with a cauliflower-like microstructure, granular films with terrace-featured SiC particles coexisting with Co 2 Si compound and clusters of nanometer SiC nanoplatelets appear as a function of the deposition pressure. In terms of plasma density and substrate temperature, this sequential appearance of microstructures of SiC films was explained. Adhesion tests showed that among the three types of films studied, the films with the terrace-featured SiC particles have relatively higher adhesion. Such knowledge will be of importance when the SiC films are used as interlayer between diamond films and cemented carbide substrates.

Electron gun

International Nuclear Information System (INIS)

Chen, H.-Y.; Hughes, R.H.

1979-01-01

The invention described relates to cathode ray tubes, and particularly to color picture tubes of the type useful in home television receivers and therefore to electron guns. The invention is especially applicable to self-converging tube-yoke combinations with shadow mask tubes of the type having plural-beam in-line guns disposed in a horizontal plane, an apertured mask with vertically oriented slit-shaped apertures, and a screen with vertically oriented phosphor stripes. The invention is not, however, limited to use in such tubes and may in fact be used, e.g., in dot-type shadow mask tubes and index-type tubes. (Auth.)

Operation of the APS rf gun

International Nuclear Information System (INIS)

Lewellen, J. W.

1998-01-01

The Advanced Photon Source (APS) has a thermionic-cathode rf gun system capable of providing beam to the APS linac. The gun system consists of a 1.6-cell thermionic-cathode rf gun, a fast kicker for beam current control, and an alpha magnet for bunch compression and injection into the APS linac line. This system is intended for use both as an injector for positron creation, and as a first beam source for the Low-Energy Undulator Test Line (LEUTL) project [1]. The first measured performance characteristics of the gun are presented.

Characterization of a medium-sized washer-gun for an axisymmetric mirror

Science.gov (United States)

Yi, Hongshen; Liu, Ming; Shi, Peiyun; Yang, Zhida; Zhu, Guanghui; Lu, Quanming; Sun, Xuan

2018-04-01

A new medium-sized washer gun is developed for a plasma start-up in a fully axisymmetric mirror. The gun is positioned at the east end of the Keda Mirror with AXisymmetricity facility and operated in the pulsed mode with an arc discharging time of 1.2 ms and a typical arc current of 8.5 kA with 1.5 kV discharge voltage. To optimize the operation, a systematic scan of the neutral pressure, the arc voltage, the bias voltage on a mesh grid 6 cm in front of the gun and an end electrode located on the west end of mirror, and the mirror ratio was performed. The streaming plasma was measured with triple probes in the three mirror cells and a diamagnetic loop in the central cell. Floating potential measurements suggest that the plasma could be divided into streaming and mirror-confined plasmas. The floating potential for the streaming plasma is negative, with an electric field pointing inwards. The mirror-confined plasma has a typical lifetime of 0.5 ms.

Middle Ground on Gun Control

Science.gov (United States)

2016-12-01

34 Australian Institute of Criminology, July 7, 2015, http://www.aic.gov.au/ statistics /homicide/weapon.html. 0 100 200 300 400 500 600 700 Total Gun...firearms is not the business of a single Australian , so it is immeasurably easier for politicians to categorically ban types of guns because there is...not an Australian version of Smith and Wesson that is going to be put out of business . Additionally, because all of the guns in Australia are

Camouflaged Collectives: Managing Stigma and Identity at Gun Events

Directory of Open Access Journals (Sweden)

Sarah Jane Blithe

2017-02-01

Full Text Available Gun violence persists in the United States, claiming lives and escalating healthcare costs. This article seeks to contribute to social justice work on the “gun problem” by studying gun collectives. To understand gun culture and to identify gun violence reduction strategies, we study places where gun owners organize – legal (and sometimes illegal settings that facilitate dialogue about gun issues. Based on participant observation and collaborative event ethnography at gun shows and a private shooting party, this analysis presents findings about the practices gun collective members use to manage stigma. We conclude that when participants in gun events attempt to subvert core stigma through everyday stigma management practices, they effectively facilitate the unfettered exchange of potentially dangerous goods, promote the invisibility of oppressive structures, and normalize violence.

The electrical Discharge Characteristics of the 3.5 KJ Electrothermal Plasma Gun Experiment

International Nuclear Information System (INIS)

Diab, F.; El-Aragi, G.M.; El-Kashef, G.M.; Saudy, A.H.

2013-01-01

In order to better understand the operating characteristics of an electrothermal plasma gun and its design, a variety of operation characteristics including ( the length of the capillary, applied voltage, diameter of the capillary tube, circuit inductance) were investigated to determine performance effects and viability in a real system. An Electrothermal Plasma Gun (ETG) is composed of a capillary discharge tube made of Teflon operated with simple RLC circuit. The device called Electrothermal Gun (ETG) which is composed of 4 capacitors (70 μF, 10 kV, 1.3 μH) connected in parallel to a plasma source by means of one high power plane transmission line by mean of a switch triggered by negative pulse 360/385 V. For the present studies a simple RLC was chosen, which allowed the circuit parameters to be easily measure d. The electrothermal discharge characteristics of the plasma gun operated in open air, So that at atmospheric pressure the main parameters were measured. The gun voltage and discharge current are measured with voltage divider and Rogowiski coil respectively. From the results recorded we found that, the current lagged the voltage i-e the plasma source has an inductive reactivity. Moreover, the current value was changed by changing the circuit parameters, including the discharge voltage and circuit inductance, and the wire properties such as the length and diameter. The maximum gun current ranged between (5 - 50 KA) according to the charging voltage of capacitors between (1-7 KV), a typical discharge times are on the order r of 125 μS.

Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

Directory of Open Access Journals (Sweden)

Stefan L.

2013-07-01

Full Text Available In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na+ instead of Ca2+, Na+ instead of K+. Then, the chemical evolution of cationic resins initially in the Na+ form is characterized in CEM I (Portland cement and CEM III (Portland cement + blastfurnace slag cements at early age and an explanation is proposed for the better stability of CEM III material.

Interpreting the empirical evidence on illegal gun market dynamics.

Science.gov (United States)

Braga, Anthony A; Wintemute, Garen J; Pierce, Glenn L; Cook, Philip J; Ridgeway, Greg

2012-10-01

Thousands of Americans are killed by gunfire each year, and hundreds of thousands more are injured or threatened with guns in robberies and assaults. The burden of gun violence in urban areas is particularly high. Critics suggest that the results of firearm trace data and gun trafficking investigation studies cannot be used to understand the illegal supply of guns to criminals and, therefore, that regulatory and enforcement efforts designed to disrupt illegal firearms markets are futile in addressing criminal access to firearms. In this paper, we present new data to address three key arguments used by skeptics to undermine research on illegal gun market dynamics. We find that criminals rely upon a diverse set of illegal diversion pathways to acquire guns, gun traffickers usually divert small numbers of guns, newer guns are diverted through close-to-retail diversions from legal firearms commerce, and that a diverse set of gun trafficking indicators are needed to identify and shut down gun trafficking pathways.

Experimental studies of coaxial plasma gun current

International Nuclear Information System (INIS)

Price, D.W.

1988-01-01

In this investigation of a coaxial plasma gun, plasma sheath currents and related behavior are examined. Plasma behavior in the gun affects gun characteristics. Plasma gun applications are determined by the plasma behavior. The AFWL PUFF capacitor bank (72 μF, 29 nH, 120 kV) drives the plasma gun using a deuterium fill gas. The gas breakdown site is isolated from the dielectric/vacuum interface in the AFWL system. Two gas values deliver gas in the system. The first delivers gas from the gun breech and the second optional valve delivers gas to the gun muzzle. Currents and voltages are measured by Rogowski coils, B probes and capacitive voltage probes. A O-D slug model is used to predict the current, inductance, gun voltage and plasma sheath velocity. The slug model assumes the sheath transits the gun with all mass in the sheath. In the snowplow mode, the plasma sheath is thin with a sharp current rise and drop. Our system operated in a transition mode between the snowplow and deflagration modes with early snowplow behavior and late deflagration behavior. Neutrons are produced in a plasma pinch at the gun muzzle, indicating snowplow behavior. The slug theory models overall gun behavior to experimental accuracy. Experimental results are compared to four theories for plasma sheath velocities: the Alfven collisionally limited model, the Rosenbluth model, the Fishbine saturated model and a single particle drift model. Experimental velocities vary from 10 5 to 10 6 m/s. Only the single particle drift and the slug model calculations are of the right magnitude (8 x 10 5 m/s). The Fishbine and the Rosenbluth models predict slower velocities (2 x 10 5 m/s). The Alfven model is not applicable to this system

Gun Safety (For Parents)

Science.gov (United States)

... from the home of a relative or friend. Teens should never be able to get to a gun and bullets without an adult being there. People of any age who are depressed are at increased risk of suicide. If someone in the family has depression, or has had thoughts of suicide, all guns ...

Remotely controlled spray gun

Science.gov (United States)

Cunningham, William C. (Inventor)

1987-01-01

A remotely controlled spray gun is described in which a nozzle and orifice plate are held in precise axial alignment by an alignment member, which in turn is held in alignment with the general outlet of the spray gun by insert. By this arrangement, the precise repeatability of spray patterns is insured.

Conceptual Design for CLIC Gun Pulser

Energy Technology Data Exchange (ETDEWEB)

Tang, Tao [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2016-01-08

The Compact Linear Collider (CLIC) is a proposed future electron-positron collider, designed to perform collisions at energies from 0.5 to 5 TeV, with a nominal design optimized for 3 TeV (Dannheim, 2012). The Drive Beam Accelerator consists of a thermionic DC gun, bunching section and an accelerating section. The thermionic gun needs deliver a long (~143us) pulse of current into the buncher. A pulser is needed to drive grid of the gun to generate a stable current output. This report explores the requirements of the gun pulser and potential solutions to regulate grid current.

In-Situ X-ray Tomography Study of Cement Exposed to CO2 Saturated Brine

DEFF Research Database (Denmark)

Chavez Panduro, E. A.; Torsæter, M.; Gawel, K.

2017-01-01

For successful CO2 storage in underground reservoirs, the potential problem of CO2 leakage needs to be addressed. A profoundly improved understanding of the behavior of fractured cement under realistic subsurface conditions including elevated temperature, high pressure and the presence of CO2...... saturated brine is required. Here, we report in situ X-ray micro computed tomography (μ-CT) studies visualizing the microstructural changes upon exposure of cured Portland cement with an artificially engineered leakage path (cavity) to CO2 saturated brine at high pressure. Carbonation of the bulk cement......, self-healing of the leakage path in the cement specimen, and leaching of CaCO3 were thus directly observed. The precipitation of CaCO3, which is of key importance as a possible healing mechanism of fractured cement, was found to be enhanced in confined regions having limited access to CO2...

Fueling by coaxial plasma guns

International Nuclear Information System (INIS)

Marshall, J.

1978-01-01

The operating principles of pulsed coaxial guns are reviewed. Some problems involved with the injection of plasma beams from these guns into containment fields are described. The injection during reactor operating conditions is then discussed

New Electron Gun System for BEPCII

CERN Document Server

Liu, Bo; Long Chi, Yun; Zhang, Chuang

2005-01-01

The new electron gun system for BEPCII has been put into operation since Nov. 2004. The article describes the design, experiment and operation of this new system. The design current of the gun is 10 A for the pulse lengths of 1 ns, 2.5 ns and 1 μs with repetition rate of 50 Hz. The gun is operated with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations have been carried out in the design stage, including simulation of the gun geometry and beam transportation. Some important relation curves are obtained during the experiment. Two-bunch operation is available and some elementary tests have been performed. New scheme of the gun control system based on EPICS is also presented. The real operation shows that the design and manufacturing is basically successful.

120 Hz Gun Review

Energy Technology Data Exchange (ETDEWEB)

Colby, E.

2005-01-31

The review was held at SLAC on September 11 and 12, 2001. Presentations concerning the thermal analysis, mechanical design, integration with the laser and accelerator, general beam dynamics considerations, a load lock mechanism, and symmetric power feed options comprised the review. Slides from these presentations are available elsewhere. The review committee was charged with evaluating the 120 Hz gun design including proposed load lock and power feed options and recommending improvements. Broader evaluation of the injector as a whole (including focusing and diagnostic systems that do no impact the envelope of the gun itself) is expected to be covered in a future review and will not be commented on here. In general, the long operational experience with four generations of s-band RF guns at numerous labs worldwide has led to considerable experience in design, fabrication, and operation aspects, and provides an excellent base on which to design the higher duty factor LCLS injector. While open questions remain on obtaining the design performance from these injectors, the microwave design of the gun has reached a state of relative maturity.

A thermomechanical constitutive model for cemented granular materials with quantifiable internal variables. Part II - Validation and localization analysis

Science.gov (United States)

Das, Arghya; Tengattini, Alessandro; Nguyen, Giang D.; Viggiani, Gioacchino; Hall, Stephen A.; Einav, Itai

2014-10-01

We study the mechanical failure of cemented granular materials (e.g., sandstones) using a constitutive model based on breakage mechanics for grain crushing and damage mechanics for cement fracture. The theoretical aspects of this model are presented in Part I: Tengattini et al. (2014), A thermomechanical constitutive model for cemented granular materials with quantifiable internal variables, Part I - Theory (Journal of the Mechanics and Physics of Solids, 10.1016/j.jmps.2014.05.021). In this Part II we investigate the constitutive and structural responses of cemented granular materials through analyses of Boundary Value Problems (BVPs). The multiple failure mechanisms captured by the proposed model enable the behavior of cemented granular rocks to be well reproduced for a wide range of confining pressures. Furthermore, through comparison of the model predictions and experimental data, the micromechanical basis of the model provides improved understanding of failure mechanisms of cemented granular materials. In particular, we show that grain crushing is the predominant inelastic deformation mechanism under high pressures while cement failure is the relevant mechanism at low pressures. Over an intermediate pressure regime a mixed mode of failure mechanisms is observed. Furthermore, the micromechanical roots of the model allow the effects on localized deformation modes of various initial microstructures to be studied. The results obtained from both the constitutive responses and BVP solutions indicate that the proposed approach and model provide a promising basis for future theoretical studies on cemented granular materials.

Release isentrope measurements with the LLNL electric gun

Energy Technology Data Exchange (ETDEWEB)

Gathers, G.R.; Osher, J.E.; Chau, H.H.; Weingart, R.C.; Lee, C.G.; Diaz, E.

1987-06-01

The liquid-vapor coexistence boundary is not well known for most metals because the extreme conditions near the critical point create severe experimental difficulties. The isentropes passing through the liquid-vapor region typically begin from rather large pressures on the Hugoniot. We are attempting to use the high velocities achievable with the Lawrence Livermore National Laboratory (LLNL) electric gun to obtain these extreme states in aluminum and measure the release isentropes by releasing into a series of calibrated standards with known Hugoniots. To achieve large pressure drops needed to explore the liquid-vapor region, we use argon gas for which Hugoniots have been calculated using the ACTEX code, as one of the release materials.

Porous structure analysis of radioactive spent resin cementation matrix

International Nuclear Information System (INIS)

Zhou Yaozhong; Yun Guichun

2004-01-01

According to a cement product microstructure, a radioactive spent resin cementation matrix has the properties of porous matters. The distributing of the pore size and the pore microstructure stability are closely related to many crucial macro properties, including strength and permeability of the matrixes. By using a new computer-controlled Hg pressure test, a experiment methods of the matrix micro-properties was studied. By using porous structure analyses, it was found that the experimental method is useful for the future cementation research. In this test, it was also found that ASC cement matrixes of spent resin have superior microstructure to the OPC's. They have better pore size distribution, more stable structure and higher ability to hold the Hg in the matrixes than OPC's, and these properties are the important factors that make ASC cement matrixes have more stable macro-structure and lower leaching of nuclides. (authors)

Gun Violence, mental health, and Connecticut physicians.

Science.gov (United States)

Dodds, Peter R; Anderson, Caitlyn O; Dodds, Jon H

2014-01-01

While there is a public perception that gun violence is associated with mental illness we present evidence that it is a complex public health problem which defies simple characterizations and solutions. Only a small percentage of individuals with mental illness are at risk for extreme violence and they account for only a small percentage of gun-related homicides. Individuals who are at risk for gun violence are difficult to identify and successfully treat. The incidence, and perhaps the demographics, of gun violence vary substantially from state to state. We make a case for Connecticut physicians to study gun violence at the state level. We recommend that Connecticut physicians promote and expand upon the American Academy of Pediatrics' recommendation for creating a "safe home environment. "We suggest that guns be secured in all homes in which there are children. In addition we suggest that guns be voluntarily removed from homes in which there are individuals with a history of violence, threats of violence, depression, drug and/or alcohol abuse, and individuals with major mental illnesses who are not cooperating with therapy.

Electric rail gun application to space propulsion

International Nuclear Information System (INIS)

Barber, J.P.

1979-01-01

The paper examines the possibility of using the DC electric gun principles as a space vehicle propulsion system, capable of producing intermediate thrust levels. The application of an electromagnetic launch technique, called the DC electric rail gun, to the space propulsion concept of O'Neill, is examined. It is determined that the DC electric rail gun offers very high projectile accelerations and a very significant potential for reducing the size and mass of a reaction motor for space application. A detailed description of rail gun principles is given and some simple expressions for the accelerating force, gun impedance, power supply requirements, and system performance are discussed

Association Between Substance Use and Gun-Related Behaviors.

Science.gov (United States)

Chen, Danhong; Wu, Li-Tzy

2016-01-01

Gun-related violence is a public health concern. This study synthesizes findings on associations between substance use and gun-related behaviors. Searches through PubMed, Embase, and PsycINFO located 66 studies published in English between 1992 and 2014. Most studies found a significant bivariate association between substance use and increased odds of gun-related behaviors. However, their association after adjustment was mixed, which could be attributed to a number of factors such as variations in definitions of substance use and gun activity, study design, sample demographics, and the specific covariates considered. Fewer studies identified a significant association between substance use and gun access/possession than other gun activities. The significant association between nonsubstance covariates (e.g., demographic covariates and other behavioral risk factors) and gun-related behaviors might have moderated the association between substance use and gun activities. Particularly, the strength of association between substance use and gun activities tended to reduce appreciably or to become nonsignificant after adjustment for mental disorders. Some studies indicated a positive association between the frequency of substance use and the odds of engaging in gun-related behaviors. Overall, the results suggest a need to consider substance use in research and prevention programs for gun-related violence. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Elasticity and expansion test performance of geopolymer as oil well cement

Science.gov (United States)

Ridha, S.; Hamid, A. I. Abd; Halim, A. H. Abdul; Zamzuri, N. A.

2018-04-01

History has shown that geopolymer cement provides high compressive strength as compared to Class G cement. However, the research had been done at ambient temperature, not at elevated condition which is the common oil well situation. In this research, the physical and mechanical properties performance of the oil well cement were investigated by laboratory work for two types of cement that are geopolymer and Class G cement. The cement samples were produced by mixing the cement according to the API standards. Class C fly ash was used in this study. The alkaline solution was prepared by mixing sodium silicate with NaOH solution. The NaOH solution was prepared by diluting NaOH pellets with distilled water to 8M. The cement samples were cured at a pressure of 3000 psi and a temperature of 130 °C to simulate the downhole condition. After curing, the physical properties of the cement samples were investigated using OYO Sonic Viewer to determine their elastic properties. Autoclave expansion test and compressive strength tests were conducted to determine the expansion value and the strength of the cement samples, respectively. The results showed that the geopolymer cement has a better physical and mechanical properties as compared with Class G cement at elevated condition.

Brief use of a specific gun in a violent game does not affect attitudes towards that gun.

Science.gov (United States)

Hilgard, Joseph; Engelhardt, Christopher R; Bartholow, Bruce D

2016-11-01

Although much attention has been paid to the question of whether violent video games increase aggressive behaviour, little attention has been paid to how such games might encourage antecedents of gun violence. In this study, we examined how product placement, the attractive in-game presentation of certain real-world firearm brands, might encourage gun ownership, a necessary antecedent of gun violence. We sought to study how the virtual portrayal of a real-world firearm (the Bushmaster AR-15) could influence players' attitudes towards the AR-15 specifically and gun ownership in general. College undergraduates ( N  = 176) played one of four modified video games in a 2 (gun: AR-15 or science-fiction control) × 2 (gun power: strong or weak) between-subjects design. Despite collecting many outcomes and examining many potential covariates and moderators, experimental assignment did little to influence outcomes of product evaluations or purchasing intentions with regard to the AR-15. Attitudes towards public policy and estimation of gun safety were also not influenced by experimental condition, although these might have been better tested by comparison against a no-violence control condition. By contrast, gender and political party had dramatic associations with all outcomes. We conclude that, if product placement shapes attitudes towards firearms, such effects will need to be studied with stronger manipulations or more sensitive measures.

Brief use of a specific gun in a violent game does not affect attitudes towards that gun

Science.gov (United States)

Engelhardt, Christopher R.; Bartholow, Bruce D.

2016-01-01

Although much attention has been paid to the question of whether violent video games increase aggressive behaviour, little attention has been paid to how such games might encourage antecedents of gun violence. In this study, we examined how product placement, the attractive in-game presentation of certain real-world firearm brands, might encourage gun ownership, a necessary antecedent of gun violence. We sought to study how the virtual portrayal of a real-world firearm (the Bushmaster AR-15) could influence players' attitudes towards the AR-15 specifically and gun ownership in general. College undergraduates (N = 176) played one of four modified video games in a 2 (gun: AR-15 or science-fiction control) × 2 (gun power: strong or weak) between-subjects design. Despite collecting many outcomes and examining many potential covariates and moderators, experimental assignment did little to influence outcomes of product evaluations or purchasing intentions with regard to the AR-15. Attitudes towards public policy and estimation of gun safety were also not influenced by experimental condition, although these might have been better tested by comparison against a no-violence control condition. By contrast, gender and political party had dramatic associations with all outcomes. We conclude that, if product placement shapes attitudes towards firearms, such effects will need to be studied with stronger manipulations or more sensitive measures. PMID:28018611

Nail gun injuries among construction workers.

Science.gov (United States)

Dement, John M; Lipscomb, Hester; Li, Leiming; Epling, Carol; Desai, Tejas

2003-05-01

Pneumatic nail guns greatly increase worker productivity and are extensively used in wood frame building construction, with especially high use in residential construction. One surveillance report of nail gun injuries in Washington State has been published; however, other literature consists largely of case reports and case series in trauma journals. The major objective of the current study was to investigate the occurrence of nail gun-associated injuries among construction workers and to identify preventable work-related factors associated with these injuries. Nail gun-related injuries occurring among a cohort of 13,347 carpenters in Ohio who worked union hours during the time period January 1, 1994, until September 30, 1997, were identified by matching the cohort with workers' compensation claims made to the Ohio Bureau of Workers' Compensation. We also analyzed workers' compensation claims for North Carolina Home Builders Association members for the period July 1996-November 1999 to identify nail gun-related injuries. Analyses included stratified analyses of claims by nature and body part injured, calculation of nail gun injury rates, and analyses of free text descriptions of injuries. Overall, nail gun injuries were responsible for 3.9 percent of workers' compensation claims with 8.3 percent to 25.5 percent of claims involving paid lost work time. The overall rate of nail gun injuries (cases per 200,000 work hours) was 0.33 in North Carolina and 0.26 in Ohio, reflecting the greater concentration of wood frame construction workers in the North Carolina population studied. Higher rates of injury were observed for carpenters in North Carolina and among residential carpenters in Ohio. The predominant body part injured was the hands/fingers, with 80 to 89 percent of injuries being nail punctures. Analyses of free text information for puncture injuries found approximately 70 percent of injuries to occur during the framing/sheathing stage of construction. Our data

The effect of cup outer sizes on the contact mechanics and cement fixation of cemented total hip replacements.

Science.gov (United States)

Hua, Xijin; Li, Junyan; Wang, Ling; Wilcox, Ruth; Fisher, John; Jin, Zhongmin

2015-10-01

One important loosening mechanism of the cemented total hip arthroplasty is the mechanical overload at the bone-cement interface and consequent failure of the cement fixation. Clinical studies have revealed that the outer diameter of the acetabular component is a key factor in influencing aseptic loosening of the hip arthroplasty. The aim of the present study was to investigate the influence of the cup outer diameter on the contact mechanics and cement fixation of a cemented total hip replacement (THR) with different wear penetration depths and under different cup inclination angles using finite element (FE) method. A three-dimensional FE model was developed based on a typical Charnley hip prosthesis. Two acetabular cup designs with outer diameters of 40 and 43 mm were modelled and the effect of cup outer diameter, penetration depth and cup inclination angle on the contact mechanics and cement fixation stresses in the cemented THR were studied. The results showed that for all penetration depths and cup inclination angles considered, the contact mechanics in terms of peak von Mises stress in the acetabular cup and peak contact pressure at the bearing surface for the two cup designs were similar (within 5%). However, the peak von Mises stress, the peak maximum principal stress and peak shear stress in the cement mantle at the bone-cement interface for the 43 mm diameter cup design were predicted to be lower compared to those for the 40 mm diameter cup design. The differences were predicted to be 15-19%, 15-22% and 18-20% respectively for different cup penetration depths and inclination angles, which compares to the clinical difference of aseptic loosening incidence of about 20% between the two cup designs. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Rail gun powered by an integral explosive generator

International Nuclear Information System (INIS)

Peterson, D.R.; Fowler, C.M.

1979-01-01

We propose the use of a rail gun powered by an explosive magnetic flux compression generator built into the rail gun itself in which the rails of the gun are driven together behind the projectile by explosives. The magnetic field established between the rails by an initial current supplied by an external source at the breech of the gun is trapped and compressed by the collapsing rails to accelerate the projectile down the bore of the gun

GUN4-Porphyrin Complexes Bind the ChlH/GUN5 Subunit of Mg-Chelatase and Promote Chlorophyll Biosynthesis in Arabidopsis[W

Science.gov (United States)

Adhikari, Neil D.; Froehlich, John E.; Strand, Deserah D.; Buck, Stephanie M.; Kramer, David M.; Larkin, Robert M.

2011-01-01

The GENOMES UNCOUPLED4 (GUN4) protein stimulates chlorophyll biosynthesis by activating Mg-chelatase, the enzyme that commits protoporphyrin IX to chlorophyll biosynthesis. This stimulation depends on GUN4 binding the ChlH subunit of Mg-chelatase and the porphyrin substrate and product of Mg-chelatase. After binding porphyrins, GUN4 associates more stably with chloroplast membranes and was proposed to promote interactions between ChlH and chloroplast membranes—the site of Mg-chelatase activity. GUN4 was also proposed to attenuate the production of reactive oxygen species (ROS) by binding and shielding light-exposed porphyrins from collisions with O2. To test these proposals, we first engineered Arabidopsis thaliana plants that express only porphyrin binding–deficient forms of GUN4. Using these transgenic plants and particular mutants, we found that the porphyrin binding activity of GUN4 and Mg-chelatase contribute to the accumulation of chlorophyll, GUN4, and Mg-chelatase subunits. Also, we found that the porphyrin binding activity of GUN4 and Mg-chelatase affect the associations of GUN4 and ChlH with chloroplast membranes and have various effects on the expression of ROS-inducible genes. Based on our findings, we conclude that ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes and that mutant alleles of GUN4 and Mg-chelatase genes cause sensitivity to intense light by a mechanism that is potentially complex. PMID:21467578

Rate control for electron gun evaporation

International Nuclear Information System (INIS)

Schellingerhout, A.J.G.; Janocko, M.A.; Klapwijk, T.M.; Mooij, J.E.

1989-01-01

Principles for obtaining high-quality rate control for electron gun evaporation are discussed. The design criteria for rate controllers are derived from this analysis. Results are presented which have been obtained with e-guns whose evaporation rate is controlled by a Wehnelt electrode or by sweeping of the electron beam. Further improvements of rate stability can be obtained by improved design of e-guns and power supplies

Background Checks for all Gun Buyers and Gun Violence Restraining Orders: State Efforts to Keep Guns from High-Risk Persons.

Science.gov (United States)

Vernick, Jon S; Alcorn, Ted; Horwitz, Joshua

2017-03-01

There were more than 36,000 firearm-related deaths in the U.S. in 2015. Under federal law, a background check is required only for gun purchases from licensed dealers. Research suggests that some persons prohibited from owning a gun turn to private sellers, including those identified online, to attempt to obtain a firearm. State-level approaches to make it more difficult for high-risk persons to purchase or possess firearms include universal background check (UBC) and gun violence restraining order (GVRO) laws. UBC laws, on the books in 18 states as of the end of 2016, can reduce both homicide and suicide rates. After Colorado adopted a UBC law in 2013, the number of background checks conducted by private sellers for sales occurring at places other than gun shows steadily increased. GVRO laws give law enforcement and families the authority to petition a court to temporarily remove firearms from an individual who presents a danger to himself or others during times of crisis, regardless of whether that person has been diagnosed with a mental illness. California enacted a GVRO law in 2014. Data are emerging to suggest the effectiveness of GVRO-type laws at averting suicides and providing an entryway to services.

A modified PMMA cement (Sub-cement) for accelerated fatigue testing of cemented implant constructs using cadaveric bone.

Science.gov (United States)

Race, Amos; Miller, Mark A; Mann, Kenneth A

2008-10-20

Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

Characterisation and modelling of blended cements and their application to radioactive waste immobilisation

International Nuclear Information System (INIS)

Glasser, F.P.; Atkins, M.; Kindness, A.

1991-01-01

Various aspects of the chemistry of cements, including blends with FA and BFS, pertinent to the immobilization of radioactive waste are described. The methodology and development of a model for predicting the solid and liquid phase composition in aged cement blends are given. Experimental work, backed up by thermodynamic calculations (where possible), has given valuable insight into some of the important interactions between selected (active and inactive) radwaste components and cements. The effects of elevated pressure and temperature on blended cement are also investigated. (author)

Testing a GaAs cathode in SRF gun

International Nuclear Information System (INIS)

Wang, E.; Kewisch, J.; Ben-Zvi, I.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

2011-01-01

RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10 -12 Torr because of cryo-pumping at 2K. With conventional activation of bulk GaAs, we obtained a QE of 10% at 532 nm, with lifetime of more than 3 days in the preparation chamber and have shown that it can survive in transport from the preparation chamber to the gun. The beam line has been assembled and we are exploring the best conditions for baking the cathode under vacuum. We report here the progress of our test of the GaAs cathode in the SRF gun. Future particle accelerators, such as eRHIC and the ILC require high-brightness, high-current polarized electrons. Strained superlattice GaAs:Cs has been shown to be an efficient cathode for producing polarized electrons. Activation of GaAs with Cs,O(F) lowers the electron affinity and makes it energetically possible for all the electrons, excited into the conduction band that drift or diffuse to the emission surface, to escape into the vacuum. Presently, all operating polarized electron sources, such as the CEBAF, are DC guns. In these devices, the excellent ultra-high vacuum extends the lifetime of the cathode. However, the low field gradient on the photocathode's emission surface of the DC guns limits the beam quality. The higher accelerating gradients, possible in the RF guns, generate a far better beam. Until recently, most RF guns operated at room temperature, limiting the vacuum to ∼10 -9 Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and the high accelerating

Extended suicide using an atypical stud gun.

Science.gov (United States)

Hagemeier, L; Schyma, C; Madea, B

2009-08-10

Suicides with stud guns are uncommon, but are well documented in the literature. On rare occasions, stud guns are also used as a homicide weapon. This case report describes an extended suicide in which a husband killed his wife and their two dogs, which lived on the property. The husband then committed suicide with a shot from the stud gun into his skull. He was a 70-year-old pensioner, a retired butcher, who was found by his son. He was lying in a supine position on a carpet in the living room, with the stud gun stuck in his skull. During autopsy, high concentrations of an antihistamine were found in the blood of each corpse; this drug is used as a soporific. In contrast to the literature, which mainly describes powder deposits due to the use of conventional stud guns, in this case a stud gun was used in which the expanding gases and powder escaped together with the central bolt at the front of the device; powder drains were not involved. Detailed findings of the autopsy are given with reference to this type of stud gun.

Solid state cesium ion guns for surface studies

International Nuclear Information System (INIS)

Souzis, A.E.; Carr, W.E.; Kim, S.I.; Seidl, M.

1990-01-01

Three cesium ion guns covering the energy range of 5--5000 V are described. These guns use a novel source of cesium ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using cesium vapor and porous tungsten ionizers. It has been used in ultrahigh-vacuum (UHV) experiments at pressures of -10 Torr with no significant gas load. Three different types of extraction optics are used depending on the energy range desired. For low-energy deposition, a simple space-charge-limited planar diode with a perveance of 1x10 -7 A/V 3/2 is used. Current densities of 10.0 μA/cm 2 at the exit aperture for energies ≤20 V are typical. This type of source provides an alternative to vapor deposition with the advantage of precise flux calibration by integration of the ion current. For energies from 50 to 500 V and typical beam radii of 0.5 to 0.2 mm, a high perveance Pierce-type ion gun is used. This gun was designed with a perveance of 1x10 -9 A/V 3/2 and produces a beam with an effective temperature of 0.35 eV. For the energy range of 0.5 to 5 keV, the Pierce gun is used in conjunction with two Einzel lenses, enabling a large range of imaging ratios to be obtained. Beam radii of 60 to 300 μm are typical for beam currents of 50 nA to 1.0 μA

In-situ Mechanical Manipulation of Wellbore Cements as a Solution to Leaky Wells

Science.gov (United States)

Kupresan, D.; Radonjic, M.; Heathman, J.

2013-12-01

Wellbore cement provides casing support, zonal isolation, and casing protection from corrosive fluids, which are essential for wellbore integrity. Cements can undergo one or more forms of failure such as debonding at cement/formation and cement/casing interface, fracturing and defects within cement matrix. Failures and defects within cement will ultimately lead to fluids migration, resulting in inter-zonal fluid migration and premature well abandonment. There are over 27,000 abandoned oil and gas wells only in The Gulf of Mexico (some of them dating from the late 1940s) with no gas leakage monitoring. Cement degradation linked with carbon sequestration can potentially lead to contamination of fresh water aquifers with CO2. Gas leaks can particularly be observed in deviated wells used for hydraulic fracking (60% leakage rate as they age) as high pressure fracturing increases the potential for migration pathways. Experimental method utilized in this study enables formation of impermeable seals at interfaces present in a wellbore by mechanically manipulating wellbore cement. Preliminary measurements obtained in bench scale experiments demonstrate that an impermeable cement/formation and cement/casing interface can be obtained. In post-modified cement, nitrogen gas flow-through experiments showed complete zonal isolation and no permeability in samples with pre-engineered microannulus. Material characterization experiments of modified cement revealed altered microstructural properties of cement as well as changes in mineralogical composition. Calcium-silicate-hydrate (CSH), the dominant mineral in hydrated cement which provides low permeability of cement, was modified as a result of cement pore water displacement, resulting in more dense structures. Calcium hydroxide (CH), which is associated with low resistance of cement to acidic fluids and therefore detrimental in most wellbore cements, was almost completely displaced and/or integrated in CSH as a result of

Use of a two-stage light-gas gun as an injector for electromagnetic railguns

International Nuclear Information System (INIS)

Shahinpoor, M.

1989-01-01

Ablation of wall materials is known to be a major factor limiting the performance of railguns. To minimize this effect, it is desirable too inject projectiles into railgun at velocities greater than the ablation threshold velocity (6-8 km/s for copper rails). Because two-stage light-gas guns are capable of achieving such velocities, a program was initiated to design, build and evaluate the performance of a two-stage light gas gun, utilizing hydrogen gas, for use as an injector to an electromagnetic railgun. This effort is part of a project to develop a hypervelocity electromagnetic launcher (HELEOS) for use in equation-of-state studies. In this paper, the specific design features that enhance compatibility of the injector with the railgun, including a slip-joint between the injector launch tube and the coupling section to the railgun are described. The operational capabilities for using all major projectile velocity measuring techniques, such as in-bore pressure gauges, laser and CW x-ray interrupt techniques, flash x-ray and continuous in-bore velocity measurements using VISAR interferometry are also discussed. Finally an internal ballistics code for optimizing gun performance has been utilized to interpret performance data of the gun

Ready, Fire, Aim: The College Campus Gun Fight

Science.gov (United States)

Birnbaum, Robert

2013-01-01

The question of whether guns should be permitted on college and university campuses in the United States reflects the tension between two competing perspectives. America has both a robust gun culture and an equally robust (if less well known) gun-control culture. The gun culture is as American as apple pie: There may be as many as 300 million…

Modeling electron beam parameters and plasma interface position in an anode plasma electron gun with hydrogen atmosphere

Science.gov (United States)

Krauze, A.; Virbulis, J.; Kravtsov, A.

2018-05-01

A beam glow discharge based electron gun can be applied as heater for silicon crystal growth systems in which silicon rods are pulled from melt. Impacts of high-energy charged particles cause wear and tear of the gun and generate an additional source of silicon contamination. A steady-state model for electron beam formation has been developed to model the electron gun and optimize its design. Description of the model and first simulation results are presented. It has been shown that the model can simulate dimensions of particle impact areas on the cathode and anode, but further improvements of the model are needed to correctly simulate electron trajectory distribution in the beam and the beam current dependence on the applied gas pressure.

A pressure-sensitive carbon black cement composite for traffic monitoring

KAUST Repository

Monteiro, A.O.; Loredo, A.; Da Costa, Pedro M. F. J.; Oeser, M.; Cachim, P.B.

2017-01-01

Recent advances in nanotechnology have guided the development of a new generation of multifunctional construction materials. An example of this are cement-based composites, some of which can be used not just to pave roads but also to monitor them. A

DC photoemission electron guns as ERL sources

International Nuclear Information System (INIS)

Sinclair, Charles K.

2006-01-01

Very-high-voltage DC electron guns, delivering moderate duration bunches from photoemission cathodes, and followed by conventional drift bunching and acceleration, offer a practical solution for an ERL injector. In a variant of this scheme, a DC gun is placed in close proximity to a superconducting RF accelerator cavity, with few or no active elements between the gun and cavity. The principal technical challenge with such electron guns arises from field emission from the cathode electrode and its support structure. Field emission may result in voltage breakdown across the cathode-anode gap, or a punch-through failure of the insulator holding off the cathode potential, as well as lesser though still serious problems. Various means to mitigate these problems are described. The operational lifetime of high quantum efficiency photocathodes in these guns is determined by the vacuum conditions, through phenomena such as chemical poisoning and ion back-bombardment. Minimization of the field strength on electrode structures pushes high-voltage DC guns toward large dimensions and, correspondingly, large outgassing loads, but it is also true that these guns offer many opportunities for achieving excellent vacuum conditions. Good solutions to vacuum problems that had previously limited cathode lifetime have been demonstrated in recent years. Designs for DC guns presently in use and planned for the near future will be described. The parameters necessary for a 100 mA average current, very-high-voltage DC gun with a photocathode operational lifetime greater than 100 h appear to be within reach, but have yet to be demonstrated. A 1 A average current source with good cathode operational lifetime will require developments beyond the present state-of-the-art

Analysis of Premature Wear-Out of Aircraft Gun Barrel by Applying a Transmission Electron Microscopy (TEM

Directory of Open Access Journals (Sweden)

Łęczycki Krzysztof

2017-08-01

Full Text Available Firing from gun armament generates a wide range of physico-chemical phenomena contributing to the degradation of barrel material, e.g. pressure, high temperature, chemically aggressive character of post-detonation gases and friction of a driving band. In this work the technique of thin foils was used in Transmission Electron Microscopy (TEM to study the influence of physicochemical phenomena on the material microstructure of aircraft gun barrel. A mechanism and reason of premature wear-out of the barrel under consideration was also outlined by utilising light microscopy and hardness measurements.

RF gun using laser-triggered photocathode

International Nuclear Information System (INIS)

Akiyama, H.; Otake, Y.; Naito, T.; Takeuchi, Y.; Yoshioka, M.

1992-01-01

An RF gun using laser-triggered photocathode has many advantages as an injector of the linear colliders since it can generate a low emittance and high current pulsed beam. The experimental facility for the RF gun, such as an RF system, a laser system and a photocathode have been fabricated to study the fundamental characteristics. The dynamics of the RF gun has also studied by the 1D sheet beam model. (author)

A light-gas gun for acceleration of pellets of solid D2

International Nuclear Information System (INIS)

Nordskov, A.; Skovgaard, H.; Soerensen, H.; Weisberg, K.V.

1980-10-01

A gun has been designed and built to be used for injecting solid D 2 pellets into a small tokamak for pellet-plasma interaction studies. The pellets are formed and accelerated at temperatures close to those of liquid helium. They are propelled with pressurised H 2 -gas; the pressure arises when a quantity of solid H 2 placed in the gun barrel behind the pellet is pulse heated. Pellet velocities up to 240 m/s have been obtained. The directional accuracy is better than 0.2deg and the repetition rate is one firing every five minutes. The pellet volume is 0.6 mm 3 (2 x 10 19 molecules) while the quantity of propeller gas used is around 12 x 10 19 molecules. (author)

Upgrading the JET pellet injector with a two-stage light gas gun prototype and future planning

International Nuclear Information System (INIS)

Kupschus, P.; Sonnenberg, K.; Bailey, W.; Gadeberg, M.; Hardaker, J.; Hedley, L.; Helm, J.; Flory, D.; McCarthy, P.; Nowak, A.; Twynam, P.; Szabo, T.; Watson, M.

1989-01-01

For about two years the Joint European TORUS (JET) has been using a multi-pellet injector jointly built by JET and the Oak Ridge National Laboratory (ORNL). This was and is jointly operated by a JET - US Pellet Team within the Pellet Agreement between JET and the US Department of Energy (US DOE) under the wider umbrella of the EURATOM - US DOE Agreement on collaborative Fusion Research. This injector is composed of the ORNL Launcher, employing three independently firing repetitive (up to 5 s -1 ) pneumatic guns for pellet speeds of up to 1.5 kms -1 , and a JET launcher-torus interface (Pellet Interface) which provides all required services to the launcher and its immediate control system. In particular, it provides the differential pumping to match the high pressures of the gun system to the vacuum pressure and flow requirements of the plasma boundary. The Pellet Interface, in its design from its conception about four years ago, was intended to be equipped with a JET built pellet launcher system employing also high-speed guns at a later date once the ORNL Launcher will have been removed as it is not compatible with the JET requirements for the Active Phase (tritium and remote handling compatibility). As a first step - to learn about the possible plasma physics benefits as well as to gain technical experience concerning the application of advanced gun technology, a JET two-stage light gas gun prototype has been developed and is now being installed in parallel with the ORNL Launcher. This paper reports on the JET pellet injector development program, its motivation and its results to date. It describes briefly the presently operated pellet injector, continues to outline the design of the prototype in more detail and finally sketches the plans for the near future. 8 refs., 11 figs., 1 tab

Fabrication and description of a cold cathode electron gun

International Nuclear Information System (INIS)

Sari, A.H.; Ghorannevis, M.; Hantehzadeh, M.R.; Yousefi, M.R.

2003-01-01

In this study the structure and schematic configuration of a cold cathode electron gun has been shown, which use obstructed discharge for electron producing. This type of discharge and mechanism of secondary electron emission by ions and fast neutral interaction have been described. The experiment starts in pressure of 1*10 -3 torr, in existence of helium gas. A negative DC voltage apply to a concave cathode up to -20 k V which determine electron energy

Comparison of the leachability of three TRU cement waste forms

International Nuclear Information System (INIS)

Ross, W.A.; Westsik, J.H. Jr.; Roberts, F.P.; Harvey, C.O.

1982-11-01

Cement waste forms prepared by three processes, casting, cold pressing, and FUETAP (Formed Under Elevated Temperatures and Pressure) have been compared for their leachability by using the MCC-1 leach test. The results indicate that releases of plutonium are not controlled by the waste form matrix and that there is no significant overall advantage to any of the three cement processes from a leachability viewpoint

[Significance of bone mineral density and modern cementing technique for in vitro cement penetration in total shoulder arthroplasty].

Science.gov (United States)

Pape, G; Raiss, P; Kleinschmidt, K; Schuld, C; Mohr, G; Loew, M; Rickert, M

2010-12-01

Loosening of the glenoid component is one of the major causes of failure in total shoulder arthroplasty. Possible risk factors for loosening of cemented components include an eccentric loading, poor bone quality, inadequate cementing technique and insufficient cement penetration. The application of a modern cementing technique has become an established procedure in total hip arthroplasty. The goal of modern cementing techniques in general is to improve the cement-penetration into the cancellous bone. Modern cementing techniques include the cement vacuum-mixing technique, retrograde filling of the cement under pressurisation and the use of a pulsatile lavage system. The main purpose of this study was to analyse cement penetration into the glenoid bone by using modern cement techniques and to investigate the relationship between the bone mineral density (BMD) and the cement penetration. Furthermore we measured the temperature at the glenoid surface before and after jet-lavage of different patients during total shoulder arthroplasty. It is known that the surrounding temperature of the bone has an effect on the polymerisation of the cement. Data from this experiment provide the temperature setting for the in-vitro study. The glenoid surface temperature was measured in 10 patients with a hand-held non-contact temperature measurement device. The bone mineral density was measured by DEXA. Eight paired cadaver scapulae were allocated (n = 16). Each pair comprised two scapulae from one donor (matched-pair design). Two different glenoid components were used, one with pegs and the other with a keel. The glenoids for the in-vitro study were prepared with the bone compaction technique by the same surgeon in all cases. Pulsatile lavage was used to clean the glenoid of blood and bone fragments. Low viscosity bone cement was applied retrogradely into the glenoid by using a syringe. A constant pressure was applied with a modified force sensor impactor. Micro-computed tomography

Gun possession among American youth: a discovery-based approach to understand gun violence.

Science.gov (United States)

Ruggles, Kelly V; Rajan, Sonali

2014-01-01

To apply discovery-based computational methods to nationally representative data from the Centers for Disease Control and Preventions' Youth Risk Behavior Surveillance System to better understand and visualize the behavioral factors associated with gun possession among adolescent youth. Our study uncovered the multidimensional nature of gun possession across nearly five million unique data points over a ten year period (2001-2011). Specifically, we automated odds ratio calculations for 55 risk behaviors to assemble a comprehensive table of associations for every behavior combination. Downstream analyses included the hierarchical clustering of risk behaviors based on their association "fingerprint" to 1) visualize and assess which behaviors frequently co-occur and 2) evaluate which risk behaviors are consistently found to be associated with gun possession. From these analyses, we identified more than 40 behavioral factors, including heroin use, using snuff on school property, having been injured in a fight, and having been a victim of sexual violence, that have and continue to be strongly associated with gun possession. Additionally, we identified six behavioral clusters based on association similarities: 1) physical activity and nutrition; 2) disordered eating, suicide and sexual violence; 3) weapon carrying and physical safety; 4) alcohol, marijuana and cigarette use; 5) drug use on school property and 6) overall drug use. Use of computational methodologies identified multiple risk behaviors, beyond more commonly discussed indicators of poor mental health, that are associated with gun possession among youth. Implications for prevention efforts and future interdisciplinary work applying computational methods to behavioral science data are described.

Gun possession among American youth: a discovery-based approach to understand gun violence.

Directory of Open Access Journals (Sweden)

Kelly V Ruggles

Full Text Available OBJECTIVE: To apply discovery-based computational methods to nationally representative data from the Centers for Disease Control and Preventions' Youth Risk Behavior Surveillance System to better understand and visualize the behavioral factors associated with gun possession among adolescent youth. RESULTS: Our study uncovered the multidimensional nature of gun possession across nearly five million unique data points over a ten year period (2001-2011. Specifically, we automated odds ratio calculations for 55 risk behaviors to assemble a comprehensive table of associations for every behavior combination. Downstream analyses included the hierarchical clustering of risk behaviors based on their association "fingerprint" to 1 visualize and assess which behaviors frequently co-occur and 2 evaluate which risk behaviors are consistently found to be associated with gun possession. From these analyses, we identified more than 40 behavioral factors, including heroin use, using snuff on school property, having been injured in a fight, and having been a victim of sexual violence, that have and continue to be strongly associated with gun possession. Additionally, we identified six behavioral clusters based on association similarities: 1 physical activity and nutrition; 2 disordered eating, suicide and sexual violence; 3 weapon carrying and physical safety; 4 alcohol, marijuana and cigarette use; 5 drug use on school property and 6 overall drug use. CONCLUSIONS: Use of computational methodologies identified multiple risk behaviors, beyond more commonly discussed indicators of poor mental health, that are associated with gun possession among youth. Implications for prevention efforts and future interdisciplinary work applying computational methods to behavioral science data are described.

Design of the BEPCII electron gun system

International Nuclear Information System (INIS)

Liu Bo; Gu Mengping; Chi Yunlong

2006-01-01

BEPCII upgrading project needs a new high current electron gun. The design stage such as physical design, mechanical design and control system design of this new electron gun is described. The emission current is designed to be higher than 10 A for the pulse width of 1 ns with repetition rate of 50 Hz. The gun will operate with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations and optimizations have been carried out in the design stage, including the gun geometry and beam transport. EGUN and DGUN codes are used to simulate the gun geometry, and the results show that the perveance is about 0.22 μA·V -3/2 , and the emittance at gun exit is about 16 π·mm·mrad. PARMELA code shows that the electron beam can be easily transported to the end of the first accelerating tube with a capture efficiency of 67% and root mean square emittance of 25 mm·mrad. New scheme of the gun control system based on EPICS is also presented. Two-bunch operation mode and 2.5 μs long pulse operation mode are available in the control system. (authors)

Research on Miniature Calibre Rail-Guns for the Mechanical Arm

Directory of Open Access Journals (Sweden)

Ronggang Cao

2017-01-01

Full Text Available Rail-gun should not only be used to military applications, but also can be developed as applications in the civilian aspects of the market. With the development of the electromagnetic launch technology, based on the similarity theory, using the existing rail-gun model to guide the construction of more economical miniature calibre rail-guns, and apply it in some machinery and equipment, this idea will open up a wider rail-gun application space. This article will focus on the feasibility of application of miniature calibre rail-guns in the mechanical arm. This paper designs the schematic diagram, then theoretical analyzes force conditions of the armature in the mechanical arm, calculates the possible range of the current amplitude and so on. The existing rail-gun model can be used to guides design the circuit diagram of the miniature calibre rail-gun. Based on the similarity theory and many simulation experiments, designed the experimental parameters of a miniature rail-gun and analyzed the current, Lorentz force, velocity, and location of the existing rail-gun and miniature rail-gun. The results show that the rail-gun launching technology applied to robot arms is feasibility. The application of miniature calibre rail-guns in the mechanical arm will benefit to the further development of rail-guns.

Recent developments of a two-stage light gas gun for pellet injection

International Nuclear Information System (INIS)

Reggiori, A.

1984-01-01

A report is given on a two-stage pneumatic gun operated with ambient air as first stage driver which has been built and tested. Cylindrical polyethylene pellets of 1 mm diameter and 1 mm length have been launched at velocities up to 1800 m/s, with divergence angles of the pellet trajectory less than 1 0 . It is possible to optimize the pressure pulse for pellets of different masses, simply changing the mass of the piston and/or the initial pressures in the second stage. (author)

Development of Gradient Cemented Carbides Through ICME Strategy

Science.gov (United States)

Du, Yong; Peng, Yingbiao; Zhang, Weibin; Chen, Weimin; Zhou, Peng; Xie, Wen; Cheng, Kaiming; Zhang, Lijun; Wen, Guanghua; Wang, Shequan

An integrated computational materials engineering (ICME) including CALPHAD method is a powerful tool for materials process optimization and alloy design. The quality of CALPHAD-type calculations is strongly dependent on the quality of the thermodynamic and diffusivity databases. The development of a thermodynamic database, CSUTDCC1, and a diffusivity database, CSUDDCC1, for cemented carbides is described. Several gradient cemented carbides sintered under vacuum and various partial pressures of N2 have been studied via experiment and simulation. The microstructure and concentration profile of the gradient zones have been investigated via SEM and EPMA. Examples of ICME applications in design and manufacture for different kinds of cemented carbides are shown using the databases and comparing where possible against experimental data, thereby validating its accuracy.

The electron gun for the Daresbury SRS linac

International Nuclear Information System (INIS)

Dykes, D.M.

1996-01-01

The electron gun for the Daresbury SRS linac injector has been modified to use the cathode-grid assembly from the Eimac planar triode 8755. The gun now has improved beam characteristics, is more reliable and the cathode assembly is quicker and easier to change. This paper describes the assembly of the electron gun, and then the re-conditioning of the cathode highlighting the vacuum environment. The action of the grid modulation system on the electron beam, which pre-bunches the electron beam, is described, and typical gun characteristics are shown. Proposed developments to the gun system are discussed. (author)

Simulation of electron beam from two strip electron guns and control of power density by rotation of gun

International Nuclear Information System (INIS)

Sahu, G K; Baruah, S; Thakur, K B

2012-01-01

Electron beam is preferably used for large scale evaporation of refractory materials. Material evaporation from a long and narrow source providing a well collimated wedge shaped atomic beam has applications in isotopic purification of metals relevant to nuclear industry. The electron beam from an electron gun with strip type filament provides a linear heating source. However, the high power density of the electron beam can lead to turbulence of the melt pool and undesirable splashing of molten metal. For obtaining quiet surface evaporation, the linear electron beam is generally scanned along its length. To further reduce the power density to maintain quiet evaporation the width of the vapour source can be controlled by rotating the electron gun on its plane, thereby scanning an inclined beam over the molten pool. The rotation of gun has further advantages. When multiple strip type electron guns are used for scaling up evaporation length, a dark zone appears between two beams due to physical separation of adjacent guns. This dark zone can be reduced by rotating the gun and thereby bringing two adjacent beams closer. The paper presented here provides the simulation results of the electron beam trajectory and incident power density originating from two strip electron guns by using in-house developed code. The effect of electron gun rotation on the electron beam trajectory and power density is studied. The simulation result is experimentally verified with the image of molten pool and heat affected zone taken after experiment. This technique can be gainfully utilized in controlling the time averaged power density of the electron beam and obtaining quiet evaporation from the metal molten pool.

Mole gun injury.

Science.gov (United States)

Pistré, V; Rezzouk, J

2013-09-01

A mole gun is a weapon, which is used to trap and kill moles. This report provides an overview of the state of knowledge of mole gun injuries, comparable to blast injuries caused by fireworks, explosive or gunshot. Over a 2-year period, the authors reported their experience with ten hand injuries caused by mole gun. Radial side of the hand was often concerned, particularly the thumb. The authors explain their choices in the management of such lesions. Surgery was performed primarily and a large debridement currently seemed to offer the best outcome for the patient. Blast, crush, burns and lacerations may explain the higher rate of amputation to the digits. A long period of physiotherapy, specifically of the hand, was needed before the patient could return to work. This ballistic hand trauma encountered by surgeons requires knowledge and understanding of these injuries. It should be in accordance with firearms law because of severe injuries encountered and possible lethal wounds. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Design, development and characterization of tetrode type electron gun system for generation of low energy electrons

International Nuclear Information System (INIS)

Deore, A.V.; Bhoraskar, V.N.; Dhole, S.D.

2011-01-01

A tetrode type electron gun system for the generation of low energy electrons was designed, developed and characterized. An electron gun having four electrodes namely cathode, focusing electrode, control electrode and anode has been designed for the irradiation experiments. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum upto 100 μA. The electron gun and a faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the faraday cup and irradiated with low energy electrons at a pressure around 10 -6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi electrode assembly and found to be well within 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric materials. (author)

New pulsating casing collar to improve cementing quality

Energy Technology Data Exchange (ETDEWEB)

Chen, P. [Southwest Petroleum Inst., Nanchong, Sichuan (China); He, K. [JiangHan Petroleum Administration Bureau, Qianjiang, Hubei (China); Wu, J. [Chevron Petroleum Tech. Co., Houston, TX (United States)

1998-12-31

This paper presents the design and test results of a new pulsating casing collar which improves cementing quality. The new pulsating casing collar (PCC) is designed according to the Helmholtz oscillator to generate a pulsating jet flow by self-excitation in the cementing process. By placing this new pulsating casing collar at the bottom of casing string, the generated pulsating jet flow transmits vibrating pressure waves up through the annulus and helps remove drilling mud in the annulus. It can therefore improve cementing quality, especially when eccentric annulus exists due to casing eccentricity where the mud is difficult to remove. The new pulsating casing collar consists of a top nozzle, a resonant chamber, and a bottom nozzle. It can be manufactured easily and is easy to use in the field. It has been tested in Jianghan oil-field, P.R. China. The field-test results support the theoretical analysis and laboratory test, and the cementing quality is shown greatly improved by using the new pulsating casing collar.

78 FR 66840 - Revocation of Certain Requirements Pertaining to Caps Intended for Use With Toy Guns and Toy Guns...

Science.gov (United States)

2013-11-07

... Certain Requirements Pertaining to Caps Intended for Use With Toy Guns and Toy Guns Not Intended for Use With Caps AGENCY: Consumer Product Safety Commission. ACTION: Final rule. SUMMARY: Section 106 of the... regulations pertaining to caps intended for use with toy guns refer to obsolete equipment, but the ASTM F963...

Development of coaxial rotating-plasma gun

International Nuclear Information System (INIS)

Ikehata, Takashi; Tanabe, Toshio; Mase, Hiroshi

1985-01-01

A rotating-plasma gun has been devised to produce plasma streams with higher rotational velocities. The working mechanism of the gun and the results of a preliminary experiment have been described. (author)

Plural beam electron gun assembly

International Nuclear Information System (INIS)

Stratton, M.G.

1977-01-01

The invention relates to a cathode ray tube plural-beam-in-line bi-potential electron gun assembly, having applied beam currents of differing levels, manifests structurally modified gun structures to effect focused beam landings at the screen that are evidenced as substantially equi-sized spots thereby providing improved resolution and brightness of the screen imagery. The structural changes embody modifications of the related focusing and accelerator electrodes of the respective guns to provide a partial telescoping arrangement for effecting the discrete placement, forming and shielding of the final focusing lenses. The three lenses so formed are in different planes in partial overlapping axial relationship

Application of Carbonate Looping to Cement Industry

DEFF Research Database (Denmark)

Lin, Weigang; Illerup, Jytte Boll; Dam-Johansen, Kim

2012-01-01

In the present work, cycle experiments of different types of limestone, cement raw meal and a mixture of limestone and clay were carried out in laboratory scale setups at more realistic conditions (i.e. calcination temperature is 950°C and CO2 concentration is 80%) to simulate the performance...... with an increase in the CO2 partial pressure during calcination, indicating enhancement of sintering by the presence of CO2. As sorbents, cement raw meal and the mixture of limestone and clay show a similar trend as limestone with respect to the decay of the CO2 carrying capacity and this capacity is lower than...... that of limestone at the same conditions in most cases. SEM and XRD analyses indicate that a combination of severe sintering and formation of calcium silicates attributes to the poor performance of the cement raw meal....

Brief use of a specific gun in a violent game does not affect attitudes towards that gun

OpenAIRE

Hilgard, Joseph; Engelhardt, Christopher R.; Bartholow, Bruce D.

2016-01-01

Although much attention has been paid to the question of whether violent video games increase aggressive behaviour, little attention has been paid to how such games might encourage antecedents of gun violence. In this study, we examined how product placement, the attractive in-game presentation of certain real-world firearm brands, might encourage gun ownership, a necessary antecedent of gun violence. We sought to study how the virtual portrayal of a real-world firearm (the Bushmaster AR-15) ...

Gun ownership and firearm-related deaths.

Science.gov (United States)

Bangalore, Sripal; Messerli, Franz H

2013-10-01

A variety of claims about possible associations between gun ownership rates, mental illness burden, and the risk of firearm-related deaths have been put forward. However, systematic data on this issue among various countries remain scant. Our objective was to assess whether the popular notion "guns make a nation safer" has any merits. Data on gun ownership were obtained from the Small Arms Survey, and for firearm-related deaths from a European detailed mortality database (World Health Organization), the National Center for Health Statistics, and others. Crime rate was used as an indicator of safety of the nation and was obtained from the United Nations Surveys of Crime Trends. Age-standardized disability-adjusted life-year rates due to major depressive disorder per 100,000 inhabitants with data obtained from the World Health Organization database were used as a putative indicator for mental illness burden in a given country. Among the 27 developed countries, there was a significant positive correlation between guns per capita per country and the rate of firearm-related deaths (r = 0.80; P ownership and mental illness as independent covariates, gun ownership was a significant predictor (P <.0001) of firearm-related deaths, whereas mental illness was of borderline significance (P = .05) only. The number of guns per capita per country was a strong and independent predictor of firearm-related death in a given country, whereas the predictive power of the mental illness burden was of borderline significance in a multivariable model. Regardless of exact cause and effect, however, the current study debunks the widely quoted hypothesis that guns make a nation safer. Copyright © 2013 Elsevier Inc. All rights reserved.

Ion plasma electron gun

International Nuclear Information System (INIS)

Wakalopulos, G.

1976-01-01

In the disclosed electron gun positive ions generated by a hollow cathode plasma discharge in a first chamber are accelerated through control and shield grids into a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode causing the cathode to emit secondary electrons which form an electron beam having a distribution adjacent to the cathode emissive surface substantially the same as the distribution of the ion beam impinging upon the cathode. After passing through the grids and the plasma discharge chamber, the electron beam exits from the electron gun via a foil window. Control of the generated electron beam is achieved by applying a relatively low control voltage between the control grid and the electron gun housing (which resides at ground potential) to control the density of the positive ions bombarding the cathode

SSRL photocathode RF gun test stand

International Nuclear Information System (INIS)

Hernandez, M.; Baltay, M.; Boyce, A.

1995-01-01

A photocathode RF gun test stand designed for the production and study of high brightness electron beams will be constructed at SSRL. The beam will be generated from a laser driven third generation photocathode RF gun being developed in collaboration with BNL, LBL, and UCLA. The 3-5 [MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section, in order to achieve the desired low emittance beam, emittance compensation with solenoidal focusing will be employed

Patterns of gun deaths across US counties 1999-2013.

Science.gov (United States)

Kalesan, Bindu; Galea, Sandro

2017-05-01

We examined the socio-demographic distribution of gun deaths across 3143 counties in 50 United States' states to understand the spatial patterns and correlates of high and low gun deaths. We used aggregate counts of gun deaths and population in all counties from 1999 to 2013 from the Centers for Disease Control and Prevention's Wide-ranging Online Data for Epidemiologic Research (WONDER). We characterized four levels of gun violence, as distinct levels of gun death rates of relatively safe, unsafe, violent, and extremely violent counties, based on quartiles of 15-year county-specific gun death rates per 100,000 and used negative binomial regression models allowing clustering by state to calculate incidence rate ratios and 95% confidence intervals (95% CIs). Most states had at least one violent or extremely violent county. Extremely violent gun counties were mostly rural, poor, predominantly minority, had high unemployment rate and homicide rate. Overall, homicide rate was significantly associated with gun deaths (incidence rate ratios = 1.08, 95% CI = 1.06-1.09). In relatively safe counties, this risk was 1.09 (95% CI = 1.05-1.13) and in extremely violent gun counties was 1.03 (95% CI = 1.03-1.04). There are broad differences in gun death rates across the United States representing different levels of gun death rates in each state with distinct socio-demographic profiles. Copyright © 2017 Elsevier Inc. All rights reserved.

Performance of Cement Containing Laterite as Supplementary Cementing Material

Directory of Open Access Journals (Sweden)

Abbas Bukhari, Z. S.

2013-03-01

Full Text Available The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM. The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM, laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013

Status and future prospects of SRF gun developments

International Nuclear Information System (INIS)

Teichert, Jochen

2006-01-01

While the concepts of DC and normal-conducting photo-injectors are well proofed, the SRF gun development still possesses a high risk. Challenges are the thermal and contaminant isolation needed between the cathode and superconducting cavity, the choice of the right photocathode and its life time, the difficulty of coupling high-average power into the gun, and beam excitation of higher order cavity modes. But in combination with SRF linacs, the SRF guns are the best solution for high current and CW operation. Thus, several R and D projects of SRF gun have been launched. The talk will give an overview of the history and progress of the SRF gun development. In more detail the technical concept, performance, and status of the Rossendorf superconducting RF gun project, a collaboration of BESSY, DESY, MBI and FZR, will be presented. (author)

Acute Alcohol Consumption, Alcohol Outlets, and Gun Suicide

Science.gov (United States)

Branas, Charles C.; Richmond, Therese S.; Ten Have, Thomas R.; Wiebe, Douglas J.

2014-01-01

A case–control study of 149 intentionally self-inflicted gun injury cases (including completed gun suicides) and 302 population-based controls was conducted from 2003 to 2006 in a major US city. Two focal independent variables, acute alcohol consumption and alcohol outlet availability, were measured. Conditional logistic regression was adjusted for confounding variables. Gun suicide risk to individuals in areas of high alcohol outlet availability was less than the gun suicide risk they incurred from acute alcohol consumption, especially to excess. This corroborates prior work but also uncovers new information about the relationships between acute alcohol consumption, alcohol outlets, and gun suicide. Study limitations and implications are discussed. PMID:21929327

Simple light gas guns for hypervelocity studies

International Nuclear Information System (INIS)

Combs, S.K.; Haselton, H.H.; Milora, S.L.

1990-01-01

Two-stage light guns are used extensively in hypervelocity research. The applications of this technology include impact studies and special materials development. Oak Ridge National Laboratory (ORNL) has developed two-stage guns that accelerate small projectiles (4-mm nominal diameter) to velocities of up to ∼5 km/s. These guns are relatively small and simple (thus, easy to operate), allowing a significant number of test shots to be carried out and data accumulated in a short time. Materials that have been used for projectiles include plastics, frozen isotopes of hydrogen, and lithium hydride. One gun has been used to demonstrate repetitive operation at a rate of 0.7 Hz; and, with a few design improvements, it appears capable of performing at firing frequencies of 1--2 Hz. A schematic of ORNL two-stage device is shown below. Unlike most such devices, no rupture disks are used. Instead, a fast valve (high-flow type) initiates the acceleration process in the first stage. Projectiles can be loaded into the gun breech via the slide mechanism; this action has been automated which allows repetitive firing. Alternatively, the device is equipped with ''pipe gun'' apparatus in which gas can be frozen in situ in the gun barrel to form the projectile. This equipment operates with high reliability and is well suited for small-scale testing at high velocity. 17 refs., 6 figs., 2 tabs

Separating Batterers and Guns: A Review and Analysis of Gun Removal Laws in 50 States

Science.gov (United States)

Frattaroli, Shannon; Vernick, Jon S.

2006-01-01

Firearms play an important role in lethal domestic violence incidents. The authors review state laws regarding two policies to separate batterers from firearms: laws authorizing police to remove firearms when responding to a domestic violence complaint ("police gun removal laws") and laws authorizing courts to order guns removed from batterers…

Numerical Evaluation of a Light-Gas Gun Facility for Impact Test

Directory of Open Access Journals (Sweden)

C. Rahner

2014-01-01

Full Text Available Experimental tests which match the application conditions might be used to properly evaluate materials for specific applications. High velocity impacts can be simulated using light-gas gun facilities, which come in different types and complexities. In this work different setups for a one-stage light-gas gun facility have been numerically analyzed in order to evaluate their suitability for testing materials and composites used as armor protection. A maximal barrel length of 6 m and a maximal reservoir pressure of a standard industrial gas bottle (20 MPa were chosen as limitations. The numerical predictions show that it is not possible to accelerate the projectile directly to the desired velocity with nitrogen, helium, or hydrogen as propellant gas. When using a sabot corresponding to a higher bore diameter, the necessary velocity is achievable with helium and hydrogen gases.

Study of Control Grid Thermionic Cathode RF Gun

CERN Document Server

Xiao, Jin; Ming, Li; Xinfan, Yang; Xumin, Shen; Yanan, Chen; Zhou, Xu

2004-01-01

In this paper, the beam loading effect of RF Gun was analyzed. To minimize the energy spread, the grid control RF Gun was introduced. The result shows that the grid congrol RF Gun can increase electron beam within 1% energy spread.

Klystron - Space-charge limited flow, guns, Perveance

International Nuclear Information System (INIS)

Isagawa, S.

1999-01-01

This paper treats Thermionic emission, Cathode as an e - emitter, Space-charge limited effect and 3/2 power law, Perveance, Beam spread due to space charge, Pierce guns, Magnetically immersed guns, Method of gun design including simulations, and Examples, mainly treating E3786, which attendees will operate above 1 MW-CW in a practical exercise course at KEK. (author). 74 refs

Gunning for accuracy: Company targets human error with 'foolproof' perforating gun

Energy Technology Data Exchange (ETDEWEB)

Ross, E.

2002-12-01

An innovative new design for a scalloped expandable perforating gun is described. The gun is manufactured in Edmonton by LRI Perforating Systems, and it aimed at reducing the chances of human error that can result in sub-optimal performance. A perforating gun is used to pierce the well's casing to allow hydrocarbons to flow into the wellbore. It consists of a carrier, a pipe with an eighth-inch thick wall that protects the explosives downhole, and an inner tube containing the explosives. The LRI system has a unique interlocking mechanism for the end plates, which are attached to either end of the thin-walled charge holder tube, in addition to other advantageous features, including a price advantage of 10 to 15 per cent. Marketing strategy is designed to interest wi reline companies that focus on vertical well applications. 1 photo.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, HVLP COATING EQUIPMENT, SHARPE MANUFACTURING COMPANY PLATINUM 2012 HVLP SPRAY GUN

Science.gov (United States)

This report presents the results of the verification test of the Sharpe Platinum 2013 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the Sharpe Platinum, which is designed for use in automotive refinishing. The test coating chosen by Sharpe Manufacturi...

Characteristics of the ETA gun

International Nuclear Information System (INIS)

Paul, A.C.; Neil, V.K.; Craig, G.D.; Fessenden, T.J.

1981-01-01

The Experimental Test Accelerator (ETA) is a linear induction device consisting of a 2.5-MV electron gun and ten 0.25-MV accelerating units designed to produce a 10-kA beam of electrons at 5 MeV. Calculations with the computer code EBQ as well as experimental measurements indicate that the current produced by the gun is limited by two phenomena. The first arises from the variation of particle energy with time during the pulse. Only particles with energy within a limited range can be transported by the focusing coils in the gun: therefore the variation of the gun's output current with time is determined by the coil settings. The second effect results from a collective interaction at sufficiently large current to cause a virtual cathode to form a few centimeters past the extraction grid. Operation in this regime results in greatly increased beam emittance and poor beam transport through the accelerator. Results of the code calculations are compared with experimental data and found to be in good agreement. (author)

Superconducting augmented rail gun (SARG)

International Nuclear Information System (INIS)

Homan, C.G.; Cummings, C.E.; Fowler, C.M.

1986-01-01

Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. Previous work evaluated an idealized system by neglecting energy dissipation effects. In this paper, the authors extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. In this paper, the authors discuss details of projectile design in depth and present preliminary results of rail gun performance

Cerebral damage caused by nail gun injury

DEFF Research Database (Denmark)

Andersen, Chris

2016-01-01

Background Accidents with nail guns are rather common, especially in the construction industry. Most injuries involve the extremities and several present with intracerebral injuries. When the patient is unconscious, it can be a big challenge to determine whether the injury is an accident, self....... The forensic examination showed lesions of intracranial surgery and minor bruises on the arms. No sign of defense injuries was found. There were no signs of malfunction of the nail gun-wielding robot. On the side of the machine, there were a handheld nail gun and the police investigated the case as a possible...... criminal act. They found bloodstains on the back of the machine. When awake, the man explained, that by accident, he had hit his head against a nail gun and as a result of this, the nail gun delivered a nail into his skull. Conclusion Sometimes, the circumstances of a case are not clear...

Geometry Optimization of DC/RF Photoelectron Gun

CERN Document Server

Chen Ping; Yu, David

2005-01-01

Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

Solidification of low-level radioactive wastes in masonry cement

International Nuclear Information System (INIS)

Zhou, H.; Colombo, P.

1987-03-01

Portland cements are widely used as solidification agents for low-level radioactive wastes. However, it is known that boric acid wastes, as generated at pressurized water reactors (PWR's) are difficult to solidify using ordinary portland cements. Waste containing as little as 5 wt % boric acid inhibits the curing of the cement. For this purpose, the suitability of masonry cement was investigated. Masonry cement, in the US consists of 50 wt % slaked lime (CaOH 2 ) and 50 wt % of portland type I cement. Addition of boric acid in molar concentrations equal to or less than the molar concentration of the alkali in the cement eliminates any inhibiting effects. Accordingly, 15 wt % boric acid can be satisfactorily incorporated into masonry cement. The suitability of masonry cement for the solidification of sodium sulfate wastes produced at boiling water reactors (BWR's) was also investigated. It was observed that although sodium sulfate - masonry cement waste forms containing as much as 40 wt % Na 2 SO 4 can be prepared, waste forms with more than 7 wt % sodium sulfate undergo catastrophic failure when exposed to an aqueous environment. It was determined by x-ray diffraction that in the presence of water, the sulfate reacts with hydrated calcium aluminate to form calcium aluminum sulfate hydrate (ettringite). This reaction involves a volume increase resulting in failure of the waste form. Formulation data were identified to maximize volumetric efficiency for the solidification of boric acid and sodium sulfate wastes. Measurement of some of the waste form properties relevant to evaluating the potential for the release of radionuclides to the environment included leachability, compression strengths and chemical interactions between the waste components and masonry cement. 15 refs., 19 figs., 9 tabs

NASA-Ames vertical gun

Science.gov (United States)

Schultz, P. H.

1984-01-01

A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

ATA injector-gun calculations

International Nuclear Information System (INIS)

Paul, A.C.

1981-01-01

ATA is a pulsed, 50 ns 10 KA, 50 MeV linear induction electron accelerator at LLNL. The ETA could be used as an injector for ATA. However the possibility of building a new injector gun for ATA, raised the question as to what changes from the ETA gun in electrode dimensions or potentials, if any, should be considered. In this report the EBQ code results for the four electrode configurations are reviewed and an attempt is made to determine the geometrical scaling laws appropriate to these ETA type gun geometries. Comparison of these scaling laws will be made to ETA operation. The characteristic operating curves for these geometries will also be presented and the effect of washer position determined. It will be shown that emittance growth will impose a limitation on beam current for a given anode potential before the virtual cathode limit is reached

ECR ion source with electron gun

Science.gov (United States)

Xie, Zu Q.; Lyneis, Claude M.

1993-01-01

An Advanced Electron Cyclotron Resonance ion source (10) having an electron gun (52) for introducing electrons into the plasma chamber (18) of the ion source (10). The ion source (10) has a injection enclosure (12) and a plasma chamber tank (14). The plasma chamber (18) is defined by a plurality of longitudinal magnets (16). The electron gun (52) injects electrons axially into the plasma chamber (18) such that ionization within the plasma chamber (18) occurs in the presence of the additional electrons produced by the electron gun (52). The electron gun (52) has a cathode (116) for emitting electrons therefrom which is heated by current supplied from an AC power supply (96) while bias potential is provided by a bias power supply (118). A concentric inner conductor (60) and Outer conductor (62) carry heating current to a carbon chuck (104) and carbon pusher (114) Which hold the cathode (116) in place and also heat the cathode (16). In the Advanced Electron Cyclotron Resonance ion source (10), the electron gun (52) replaces the conventional first stage used in prior art electron cyclotron resonance ion generators.

Revised theory of Pierce-type electron guns

International Nuclear Information System (INIS)

Sar-El, H.Z.

1982-01-01

Attempts to date to obtain the shape of the beam forming electrodes of various Pierce-type electron guns are briefly discussed with emphasis on the many discrepansis in the results of previous works. A revised theory of Pierce-type electron guns is proposed. The shapes of the beam-forming electrodes for all known configurations of Pierce guns were computed on the basis of the proposed theory. (orig.)

Gas injected washer plasma gun

International Nuclear Information System (INIS)

Jain, K.K.; John, P.I.; Punithavelu, A.M.; Rao, P.P.

1980-01-01

A plasma gun similar in geometry to the washer plasma gun has been operated with gas injected externally. hydrogen, nitrogen and argon plasmas have been ionised and accelerated to velocities of the order of 10 7 mm s -1 and densities 10 11 mm -3 . Higher parameter range is possible with higher electrical input power. (author)

Gun Concerns Personal for Duncan

Science.gov (United States)

McNeil, Michele

2013-01-01

As U.S. Secretary of Education Arne Duncan works with other Obama administration officials on policy responses to the shootings at a Connecticut elementary school, he brings a personal and professional history that has acquainted him with the impact of gun violence. As schools chief in Chicago from 2001 to 2008, he was affected by the gun deaths…

Cermet cements.

Science.gov (United States)

McLean, J W

1990-01-01

Cermet ionomer cements are sintered metal/glass powders, which can be made to react with poly(acids). These new cements are significantly more resistant to abrasion than regular glass ionomer cements and are widely accepted as core build-up materials and lining cements. They can strengthen teeth and provide the clinician with an opportunity to treat early dental caries.

FY 1974 Report on results of Sunshine Project. Research and development of cement serviceable under geothermal conditions; 1974 nendo chinetsu kankyoka de shiyo kanona cement kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1975-03-30

Researches are conducted for the (research and development of cement serviceable under geothermal conditions). The research items include (1) surveys on test apparatuses, (2) basic surveys on cement, additives and cement slurry, (3) R and D of cement, and (4) researches on cement additives and slurry. For the item (1), bright prospects are obtained that US's Chandler can supply a thickening time tester serviceable at up to 750 degrees F and 40,000 psi, and a cement curing device serviceable at up to 750 degrees F and 5,000 psi. For the item (2), the surveys are conducted on the existing techniques for curing reactions and chemical resistance of cement at elevated temperature and pressure. For the item (3), the researches are conducted to develop cement resistant to heat and sulfates for geothermal development purposes, where portland cement and mixed portland cement are used as the bases which are incorporated with silica powder. As a result, it is found that the optimum Ca/SiO{sub 2} and CaO/SiO{sub 2}+Al{sub 2}O{sub 3} molar ratios are around 1.0 to 0.9 and 0.9 to 0.8, respectively. For the item (4), the tests are conducted to determine adequate conditions of conductor pipe cementing and cement slurry for 1,500m deep geothermal wells, and the standard composition is established. (NEDO)

FY 1974 Report on results of Sunshine Project. Research and development of cement serviceable under geothermal conditions; 1974 nendo chinetsu kankyoka de shiyo kanona cement kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1975-03-30

Researches are conducted for the (research and development of cement serviceable under geothermal conditions). The research items include (1) surveys on test apparatuses, (2) basic surveys on cement, additives and cement slurry, (3) R and D of cement, and (4) researches on cement additives and slurry. For the item (1), bright prospects are obtained that US's Chandler can supply a thickening time tester serviceable at up to 750 degrees F and 40,000 psi, and a cement curing device serviceable at up to 750 degrees F and 5,000 psi. For the item (2), the surveys are conducted on the existing techniques for curing reactions and chemical resistance of cement at elevated temperature and pressure. For the item (3), the researches are conducted to develop cement resistant to heat and sulfates for geothermal development purposes, where portland cement and mixed portland cement are used as the bases which are incorporated with silica powder. As a result, it is found that the optimum Ca/SiO{sub 2} and CaO/SiO{sub 2}+Al{sub 2}O{sub 3} molar ratios are around 1.0 to 0.9 and 0.9 to 0.8, respectively. For the item (4), the tests are conducted to determine adequate conditions of conductor pipe cementing and cement slurry for 1,500m deep geothermal wells, and the standard composition is established. (NEDO)

Gun Safety Management with Patients at Risk for Suicide

Science.gov (United States)

Simon, Robert I.

2007-01-01

Guns in the home are associated with a five-fold increase in suicide. All patients at risk for suicide must be asked if guns are available at home or easily accessible elsewhere, or if they have intent to buy or purchase a gun. Gun safety management requires a collaborative team approach including the clinician, patient, and designated person…

Review of the interactions between bentonite and cement

International Nuclear Information System (INIS)

Duerden, S.L.

1992-01-01

Properties of bentonite may be significantly affected by reaction with cement. This report reviews the literature to identify the reactions that may occur and considers their effects on the performance of bentonite in these applications. The dominant reactions expected under alkaline conditions prevalent in an underground repository where cement is used extensively are zeolitization, beidellitization, and ion exchange. Zeolitisation will occur at high temperatures (200 o C) or after long periods (500-1000 years) when the pH is high (pH>9). Beidellitization may occur at high pH (pH>9). The silica may reprecipitate in situ due to low hydraulic conductivity or in regions of low pH or temperature. This may result in reduced porosity/permeability and plasticity. Ion exchange reactions are virtually instantaneous. The rate of the reaction depends on the concentration and rate of access of ground water. Substitution of Ca 2+ ions from cement for Na + ions in sodium-bentonites will result in reduced swelling pressure and plasticity, and increased hydraulic conductivity of the bentonite. The effect of Na-bentonite on the properties of cement is the formation of an Al-substituted 11A tobermorite, which results in improved Cs + sorption. In cements reacted with Calcium-bentonite the main product was found to be a hydroxyapatite layer on the cement surface. (author)

Overview and Recent Results from the HyperV Plasma Gun

Science.gov (United States)

Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

2007-11-01

We present an overview of research at HyperV to develop high velocity dense plasma jets for application to fusion and HEDP. The approach uses symmetrical pulsed injection of high density plasma into a coaxial EM accelerator having a cross-section tailored to prevent formation of the blow-by instability. Two development paths are followed to accomplish this injection step: we compare large arrays of capillary discharges to sparkgaps arranged in a toroidal configuration. Experiments on three test fixtures are described: a 2pi configuration with 64 capillary injectors, a 32 injector prototype gun designed to drive rotation in the Maryland MCX experiment, and a second gun using 112 sparkgap electrodes for injection. Data is presented from visible light spectroscopy, fast optical imaging, Rogowski coils, pressure probes, Bdot probes, photodiodes, and a laser interferometer. Ballistic pendulum tests indicate plasma jets with mass 160 micrograms at 70 km/s have been achieved with plasma density above 10^15 cm-3.

Gas gun experiments and numerical simulations on the HMX-based explosive PBX 9501 in the overdriven 30 to 120 GPa pressure regime

Science.gov (United States)

Pittman, E. R.; Gustavsen, R. L.; Hagelberg, C. R.; Schmidt, J. H.

2017-06-01

The focus of this set of experiments is the development of data on the Hugoniot for the overdriven products equation of state (EOS) of PBX 9501 (95 weight % HMX, 5 weight % plastic binder) and to extend data from which current computational EOS models draw. This series of shots was conducted using the two-stage gas-guns at Los Alamos and aimed to gather data in the 30 to 120 GPa pressure regime. Experiments were simulated using FLAG, a Langrangian multiphysics code, using a one-dimensional setup which employs the Wescott Stewart Davis (WSD) reactive burn model. Prior to this study, data did not extend above 90 GPa, so the new data allowed the model to be re-evaluated. A comparison of the simulations with the experimental data shows that the model fits well below 80 GPa. However, the model did not fall within the error bars of the data for higher pressures. This is an indication that the PBX 9501 overdriven EOS products model could be modified to better match the data.

US-guided biopsy of renal allografts using 18G biopsy gun: analysis of 200 cases

International Nuclear Information System (INIS)

Kim, Eun Kyung; Lee, Jong Tae; Kim, Myeong Jin; Yoo, Hyung Sik; Kim, Ki Whang; Park, Ki Ill; Chung, Hyun Joo

1995-01-01

We evaluated the effectiveness and safety of 18G biopsy gun with US guidance in the transplanted kidneys. We performed 200 US-guided percutaneous biopsies using 18G biopsy gun. Diagnostic efficacy and complication of the biopsy in these patients were analyzed. Biopsy specimens were adequate for histologic diagnoses in 193 patients(96.5%). The mean of the biopsy frequency was 3, the mean of total glomerular number was 21.64 and the mean glomerular number per one biopsy was 6.93. Major complications occurred in 3 (1.5%) of the 200 biopsies; hematuria developed in two patients, AV fistula in one. These complications were successfully controlled either by only transfusion or by coil embolization. There were no statistical differences in blood pressure, hemoglobin, BUN/Cr between pre-and post-renal biopsies. US-guided percutaneous biopsy of renal allograft with 18G biopsy gun is simple, safe, and accurate method in evaluating the renal allograft dysfunction

Performance of a carbon nanotube field emission electron gun

Science.gov (United States)

Getty, Stephanie A.; King, Todd T.; Bis, Rachael A.; Jones, Hollis H.; Herrero, Federico; Lynch, Bernard A.; Roman, Patrick; Mahaffy, Paul

2007-04-01

A cold cathode field emission electron gun (e-gun) based on a patterned carbon nanotube (CNT) film has been fabricated for use in a miniaturized reflectron time-of-flight mass spectrometer (RTOF MS), with future applications in other charged particle spectrometers, and performance of the CNT e-gun has been evaluated. A thermionic electron gun has also been fabricated and evaluated in parallel and its performance is used as a benchmark in the evaluation of our CNT e-gun. Implications for future improvements and integration into the RTOF MS are discussed.

Law Enforcement and Gun Retailers as Partners for Safely Storing Guns to Prevent Suicide: A Study in 8 Mountain West States.

Science.gov (United States)

Runyan, Carol W; Brooks-Russell, Ashley; Brandspigel, Sara; Betz, Marian; Tung, Gregory; Novins, Douglas; Agans, Robert

2017-11-01

To examine the extent to which law enforcement agencies (LEAs) and gun retailers are willing to offer voluntary, temporary storage as a part of an overall suicide prevention effort. We invited all LEAs and gun retailers in 8 US states to respond to questionnaires asking about their willingness to offer temporary gun storage and their recommendations to gun owners about safe storage. We collected data in 2016 from 448 LEAs and 95 retailers (response rates of 53% and 25%, respectively). Three quarters of LEAs (74.8%; 95% confidence interval [CI] = 72.1, 77.5) indicated they already provided temporary storage compared with 47.6% (95% CI = 39.2, 56.0) of retailers. LEAs were most willing to provide storage when a gun owner was concerned about the mental health of a family member. Retailers were more receptive than were LEAs to providing storage when visitors were coming or for people wanting storage while traveling. Both groups recommended locking devices within the home, but LEAs were slightly more favorable to storing guns away from the home. Law enforcement agencies and gun retailers are important resources for families concerned about suicide.

Trapping of gun-injected plasma by a tokamak

International Nuclear Information System (INIS)

Leonard, A.W.; Dexter, R.N.; Sprott, J.C.

1986-01-01

It is shown that a plasma produced by a Marshall gun can be injected into and trapped by a tokamak plasma. Gun injection raises the line-averaged density and peaks the density profile. Trapping of the gun-injected plasma is explainable in terms of a depolarization current mechanism

High Brightness Injectors Based On Photocathode DC Gun

International Nuclear Information System (INIS)

B. Yunn

2001-01-01

Sample results of new injector design method based on a photocathode dc gun are presented, based on other work analytically proving the validity of the emittance compensation scheme for the case even when beam bunching is involved. We have designed several new injectors appropriate for different bunch charge ranges accordingly. Excellent beam quality produced by these injectors clearly shows that a photocathode dc gun can compete with a rf gun on an equal footing as the source of an electron beam for the bunch charge ranging up to 2 nano Coulomb (nC). This work therefore elevates a dc gun based injector to the preferred choice for many ongoing high brightness accelerator projects considering the proven operational stability and high average power capability of the dc gun

Binding of chloride and alkalis in Portland cement systems

International Nuclear Information System (INIS)

Nielsen, Erik P.; Herfort, Duncan; Geiker, Mette R.

2005-01-01

A thermodynamic model for describing the binding of chloride and alkalis in hydrated Portland cement pastes has been developed. The model is based on the phase rule, which for cement pastes in aggressive marine environment predicts multivariant conditions, even at constant temperature and pressure. The effect of the chloride and alkalis has been quantified by experiments on cement pastes prepared from white Portland cements containing 4% and 12% C 3 A, and a grey Portland cement containing 7% C 3 A. One weight percent calcite was added to all cements. The pastes prepared at w/s ratio of 0.70 were stored in solutions of different Cl (CaCl 2 ) and Na (NaOH) concentrations. When equilibrium was reached, the mineralogy of the pastes was investigated by EDS analysis on the SEM. A well-defined distribution of chloride was found between the pore solution, the C-S-H phase, and an AFm solid solution phase consisting of Friedel's salt and monocarbonate. Partition coefficients varied as a function of iron and alkali contents. The lower content of alkalis in WPC results in higher chloride contents in the C-S-H phase. High alkali contents result in higher chloride concentrations in the pore solution

PHERMEX electron gun development

International Nuclear Information System (INIS)

Builta, L.A.; Elliott, J.C.; Moir, D.C.; Starke, T.P.; Vecere, C.A.

1983-01-01

The PHERMEX facility is a 50-MHz standing-wave linear accelerator. Electrons are injected, accelerated, and transported to a tungsten target where bremsstrahlung x rays are generated for flash radiography of hydrodynamic systems. The purpose of this article is to describe the progress of PHERMEX electron gun development. The goal of this program is to generate and transport a 200-ns, 1-MV, 1-kA electron beam into the first PHERMEX accelerating cavity. The standard gun is operated at a pulse voltage of 550 kV, which is the limit determined by internal breakdown of the vacuum insulator. This insulator has been redesigned, and the gun has been pulsed at 750 kV without internal breakdown. At present, the current output is not limited by voltage but by a phenomenon called pulse shortening, which occurs at a pulse voltage of approximately 650 kV. The phenomenon has been investigated and the results are presented

What is the level of household gun ownership in urban Mexico? An estimate from the first Mexican survey on gun ownership 2017.

Science.gov (United States)

Perez Esparza, David; Hemenway, David

2017-12-20

Gun violence has increased in Mexico since the mid-2000s, but little is known about patterns of gun ownership. We examine the size and composition of the privately held urban firearm stock in Mexico, motivations for ownership, and attitudes about gun laws. To this end, a household telephone survey of 1361 adults living in nine Mexican cities was conducted in the summer of 2017. We find that few urban Mexican households contain guns. Most of those who report ownership possess one gun, having purchased it recently for self-defense. Few urban Mexican citizens plan to purchase a gun in the future. Respondents are more likely to believe that crime in Mexico would increase if guns were allowed in more places (ie, workplaces and motor vehicles). Evidence suggests urban Mexico has relative low rates of firearm ownership. Few city dwellers plan on obtaining a firearm in the near future. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Electrothermal plasma gun as a pellet injector

International Nuclear Information System (INIS)

Kincaid, R.W.; Bourham, M.A.

1994-01-01

The NCSU electrothermal plasma gun SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets, to determine the feasibility of the use of electrothermal guns as pellet injectors. The use of an electrothermal gun to inject frozen hydrogenic pellets requires a mechanism to provide protective shells (sabots) for shielding the pellet from ablation during acceleration into and through the barrel of the gun. The gun has been modified to accommodate acceleration of the plastic pellets using special acceleration barrels equipped with diagnostics for velocity and position of the pellet, and targets to absorb the pellet's energy on impact. The length of the acceleration path could be varied between 15 and 45 cm. The discharge energy of the electrothermal gun ranged from 2 to 6 kJ. The pellet velocities have been measured via a set of break wires. Pellet masses were varied between 0.5 and 1.0 grams. Preliminary results on 0.5 and 1.0 g pellets show that the exit velocity reaches 0.9 km/s at 6 kJ input energy to the source. Higher velocities of 1.5 and 2.7 km/s have been achieved using 0.5 and 1.0 gm pellets in 30 cm long barrel, without cleaning the barrel between the shots

78 FR 11902 - Review of Gun Safety Technologies

Science.gov (United States)

2013-02-20

... DEPARTMENT OF JUSTICE Office of Justice Programs [OJP (NIJ) Docket No. 1615] Review of Gun Safety...'s Plan to reduce gun violence released on January 16, 2013, the U.S. Department of Justice, Office... emerging gun safety technologies and plans to issue a report on the availability and use of those...

Gun Access and Safety Practices among Older Adults

Directory of Open Access Journals (Sweden)

Hillary D. Lum

2016-01-01

Full Text Available Background. Given high rates of gun ownership among older adults, geriatric providers can assess firearm safety practices using a “5 Ls” approach: Locked; Loaded; Little children; feeling Low; and Learned owner. This study describes gun access and the “5 Ls” among US older adults. Methods. Data on the “5 Ls” from the Second Injury Control and Risk Survey (ICARIS-2, a national telephone survey conducted by the Centers for Disease Control and Prevention, were analyzed. Weighted variables were used to generate national estimates regarding prevalence of gun ownership and associated gun safety among older adults (≥55 years. Results. Of 2939 older adults, 39% (95% CI 37%–42% reported ≥1 gun stored at home. Among those with guns at home, 21% (95% CI 18–24% stored guns loaded and unlocked; 9.2% (95% CI 6.6–12% had ≥1 child in household; 5.1% (95% CI 3.5–6.8% reported past-year suicidal ideation and 3.6% (95% CI 2.1–5.2% reported history of a suicide attempt; and 55% (95% CI 51–59% stated that ≥1 adult had attended firearm safety workshop. Conclusion. Some older adults may be at elevated risk of firearm injury because of storage practices, suicidal thoughts, or limited safety training. Future work should assess effective approaches to reduce the risk of gun-related injuries among older adults.

A 3 GHz photoelectron gun for high beam intensity

CERN Document Server

Bossart, Rudolf; Dehler, M; Godot, J C

1996-01-01

For the Compact Linear Collider Test Facility (CTF) at CERN a new rf gun with a laser driven photocathode is under construction. The new rf gun will replace the present 11/2 cell gun and will consist of 21/2 cells accelerating the beam to a momentum of 7.0 MeV/c with an electric field strength of 100 MV/m. The strong space-charge forces at low beam energy caused by the high charge density of the electron bunches are contained by radial and longitudinal rf focusing in the gun. The rf gun under construction has been optimized by MAFIA beam simulations for an injector assembly comprising a second accelerating rf structure and an intermediate solenoid magnet correcting the beam divergence of the 21/2 cell gun. The beam loading of the rf gun, by a train of 48 bunches with 21 nC charge each, causes a strong energy decay accompanied by an increase of the flight time for the bunches with lower energy. These effects can be corrected by slightly shifting the acceleration frequency of the gun. The experimental results...

Utility of indices of gun availability in the community.

Science.gov (United States)

Shenassa, Edmond D; Daskalakis, Constantine; Buka, Stephen L

2006-01-01

To estimate the degree to which the proportion of homicides and suicides committed with a gun is associated with reported availability of firearms across Chicago neighbourhoods. Data were collected as part of the Project on Human Development in Chicago Neighborhoods (PHDCN), a combined neighbourhood and individual level study of the city of Chicago. The study used data from 837 PHDCN participants between the ages of 17 and 22, residing in 170 different neighbourhoods. Gun availability was measured via participant reports on whether they had carried a gun and whether they perceived gun access to be easy in their community. Data on suicides and homicides were obtained from the Chicago Department of Health. A 10% change in the proportion of homicides committed by a gun in a neighbourhood was associated with a 20% increase in both the odds of reported gun access and reported gun carrying (p=0.002 and 0.048, respectively). The proportion of firearm related suicides was not associated with either of those self reported measures. The proportion of firearm related homicides, but not the proportion of firearm related suicides, is a useful predictor of gun availability across small areas such as neighbourhoods.

Elastoplastic cup model for cement-based materials

Directory of Open Access Journals (Sweden)

Yan Zhang

2010-03-01

Full Text Available Based on experimental data obtained from triaxial tests and a hydrostatic test, a cup model was formulated. Two plastic mechanisms, respectively a deviatoric shearing and a pore collapse, are taken into account. This model also considers the influence of confining pressure. In this paper, the calibration of the model is detailed and numerical simulations of the main mechanical behavior of cement paste over a large range of stress are described, showing good agreement with experimental results. The case study shows that this cup model has extensive applicability for cement-based materials and other quasi-brittle and high-porosity materials in a complex stress state.

Predicting the Occurrence of Hydraulic Fracture in Grouting Operations Based on the Pressure in the Penetrated Cement Grout

Directory of Open Access Journals (Sweden)

Hassan Bakhshandeh Amnieh

2017-12-01

Full Text Available Cement grouting is an operation often carried out to consolidate and seal the rock mass in dam sites and tunnels. The quality and efficiency of a grouting operation depends on various factors such as water take, grout properties and grouting pressure. One of the parameters which have the highest effect is pressure since the application of excessive pressure causes the hydraulic fracture phenomenon to occur in the rock mass and too little pressure leads to incomplete grouting and failure to seal the site in a perfect manner. Mathematical modeling is used for the first time in this study to predict and determine the optimum pressure. Thus, the joints that exist in the rock mass are simulated using cylindrical shell model. The joint surroundings are also modeled through Pasternak environment. To obtain equations governing the joints and the surroundings, energy method is used accompanied by Hamilton principle. In the end, an analytical solution method is used to obtain the maximum grouting pressure. In order to validate the modeling, the grouting pressure values obtained by the model were used in the sites of Seymareh and Aghbolagh dams and the relative error rates were measured considering the differences between calculated and actual pressures. Modeling in the examined sections of Seymareh dam showed 29.61, 5.57, 21.98, 32.50 and 9.09 percent error rates and in the sections of Aghbolagh dam it rendered the values of 4.32, 5.40 and 2.96 percent. The results indicate that this modeling can be used to estimate the amount of pressure for hydraulic fracture in grouting, to predict it and to prevent it.

ULTRA-LIGHTWEIGHT CEMENT

International Nuclear Information System (INIS)

Fred Sabins

2001-01-01

The objective of this project is to develop an improved ultra-lightweight cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary of Halliburton Energy Services (HES) and BJ Services historical performance data for lightweight cement applications. These data are analyzed and compared to ULHS cement and foamed cement performances. Similar data is expected from Schlumberger, and an analysis of this data will be completed in the following phases of the project. Quality control testing of materials used to formulate ULHS cements in the laboratory was completed to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS and foamed cement. This protocol is presented and discussed. Results of further testing of ULHS cements are presented along with an analysis to establish cement performance design criteria to be used during the remainder of the project. Finally, a list of relevant literature on lightweight cement performance is compiled for review during the next quarter

Efficiency of Micro-fine Cement Grouting in Liquefiable Sand

International Nuclear Information System (INIS)

Mirjalili, Mojtaba; Mirdamadi, Alireza; Ahmadi, Alireza

2008-01-01

In the presence of strong ground motion, liquefaction hazards are likely to occur in saturated cohesion-less soils. The risk of liquefaction and subsequent deformation can be reduced by various ground improvement methods including the cement grouting technique. The grouting method was proposed for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. In this research, a large-scale experiment was developed for assessment of micro-fine cement grouting effect on strength behavior and liquefaction potential of loose sand. Loose sand samples treated with micro-fine grout in multidirectional experimental model, were tested under cyclic and monotonic triaxial loading to investigate the influence of micro-fine grout on the deformation properties and pore pressure response. The behavior of pure sand was compared with the behavior of sand grouted with a micro-fine cement grout. The test results were shown that cement grouting with low concentrations significantly decreased the liquefaction potential of loose sand and related ground deformation

High-level radioactive waste incorporation into (special) cements

International Nuclear Information System (INIS)

Roy, D.M.; Gouda, G.R.

1978-01-01

A feasibility study has demonstrated that very strong, durable, relatively impermeable cylinders may be prepared by hot pressing combinations of cements with simulated radioactive waste solids. While the properties have not been studied exhaustively, the results suggest an optional method for immobilization and isolation of radioactive waste. Samples prepared with calcium aluminate cements appeared to have properties superior to those with Portland cements. Four simulated radioactive waste compositions having high rare-earth oxide contents, and some containing a large excess of NaNO 3 , were studied. Modest temperatures [423 to 673 K (150 to 400 0 C)] were used for hot pressing at pressures from 178 to 345 MPa. Dense strong very low porosity specimens resulted when mixtures containing from 10 to 50% waste were hot pressed, incorporating also a small percentage of water. In addition, high-strength cement cylinders were prepared with the waste solid (approximately 20 wt% waste) in a separate core and were very resistant to leaching by water near its boiling point. With this configuration, even the NaNO 3 -containing wastes were resistant to leaching by water

Low Emittance Guns for the ILC Polarized Electron Beam

International Nuclear Information System (INIS)

Clendenin, J. E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R. E.; Maruyama, T.; Miller, R. H.; Wang, J. W.; Zhou, F.

2007-01-01

Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of ≥200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while ≥500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

Low Emittance Guns for the ILC Polarized Electron Beam

International Nuclear Information System (INIS)

Clendenin, J.E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R.E.; Maruyama, T.; Miller, R.H.; Wang, J.W.; Zhou, F.; SLAC

2006-01-01

Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of (ge)200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while (ge)500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

Advances in DC photocathode electron guns

International Nuclear Information System (INIS)

Dunham M, Bruce; Heartmann, P.; Reza Kazimi; Hongxiu Liu; Poelker, B.M.; Price, J.S.; Rutt, P.M.; Schneider, W.J.; Sinclair K, Charles

1998-01-01

At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughout. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion back-bombardment, and precise control of all of the electrons emitted from the cathode. In this paper, the authors will review recent results and discuss implications for future photocathode guns

Advances in DC photocathode electron guns

International Nuclear Information System (INIS)

Dunham, B. M.; Hartmann, P.; Kazimi, R.; Liu, H.; Poelker, B. M.; Price, J. S.; Rutt, P. M.; Schneider, W. J.; Sinclair, C. K.

1999-01-01

At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughput. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion backbombardment, and precise control of all of the electrons emitted from the cathode. In this paper, we will review recent results and discuss implications for future photocathode guns

A compact electron gun using field emitter array

International Nuclear Information System (INIS)

Asakawa, M.R.; Ikeda, A.; Miyabe, N.; Yamaguchi, S.; Kusaba, M.; Tsunawaki, Y.

2008-01-01

A compact electron gun using field emitter array has been developed. With a simple triode configuration consisting of FEA, mid-electrode and anode electrode, the electron gun produces a parallel beam with a diameter of 0.5 mm. This electron gun is applicable for compact radiation sources such as Cherenkov free-electron lasers

Development of the electron gun control system of SSRF

International Nuclear Information System (INIS)

Zhou Dayong; Lin Guoqiang; Liu Dekang; Shen Liren

2010-01-01

An electron gun is the key part of a linac, the beam quality of which depends on beam quality of the electron gun, hence the need of a stable control system of the electron gun to ensure its safe operation.In this paper, we report our progresses in developing the linac's electron gun control system of Shanghai Synchrotron Radiation Facility (SSRF). It uses PLC as the device controllers, with the monitoring software developed on EPICS. The whole system is connected by Ethernet. The PLC and Ethernet technology ensures good reliability and easy maintenance of the electron gun control system. (authors)

Characterisation of 100 kW electron beam melting gun and its adaptation as electron gun for high power DC electron accelerators

International Nuclear Information System (INIS)

Banerjee, Srutarshi; Bhattacharjee, Dhruva; Waghmare, Abhay; Tiwari, Rajnish; Bakhtsingh, R.I.; Dasgupta, K.; Gupta, Sachin; Prakash, Baibhaw; Jha, M.N.

2015-01-01

The paper deals with the characterization of the 100 kW electron beam melting gun for its adaptation in high power DC Electron Accelerators. The indigenously designed electron beam melting system at BARC is chosen for characterization. It comprises of electron gun as source of electrons, two electromagnetic focusing lenses viz. upper focusing lens and lower focusing lens for beam focusing, intermediate beam aperture for vacuum decoupling between gun region and melt zone, deflection and oscillation lens for maneuvering the beam on the melt charge and water cooled crucible that acts as a beam dump. In this system, the electron gun is designed for 40 kV and 100 kW corresponding to a maximum beam current of 2.5 A. The electron gun uses directly heated spiral tungsten filament. The operating temperature of the filament is 2800 °K. The focusing electrode and the anode profile are designed based on Pierce geometry. High Power DC Electron Accelerators require high currents of 1 A. The beam must comply with the requirement of 40 mm beam diameter and 10 mrad divergence at the exit of the electron gun. The characterization of the existing electron gun was done to find out all the beam parameters, for e.g. beam size, beam divergence, perveance etc. to be adapted or to be modified for the design of electron gun for high power DC accelerators. This paper shows limitations and the possible solutions for design of high power DC accelerators. (author)

Cement-latex grouting mortar for cementing boreholes

Energy Technology Data Exchange (ETDEWEB)

Kateev, I S; Golyshkina, L A; Gorbunova, I V; Kurochkin, B M; Vakula, Ya V

1980-01-01

The need for the development of cement-latex grouting mortar for the purpose of separating strata when reinforcing boreholes at deposits in the Tatar Associated SSR is evaluated. Results of studies of the physical and mechanical properties of cement-latex grouting mortar systems (mortar plus brick) are presented. Formulas for preparing cement-latex grouting mortor are evaluated and results of industrial tests of such mortars shown.

Spheromak experiment using separate guns for formation and sustainment

International Nuclear Information System (INIS)

Brown, M.R.; Martin, A.

1996-01-01

An experiment is described that incorporates the use of separate magnetized plasma guns for formation and sustainment of a spheromak. It is shown that energy coupling efficiency approaches unity if the gun and spheromak are of comparable size. A large gun should be able to operate at lower current and therefore lower voltage. In addition, it is expected that a gun matched to the size of the spheromak will cause less perturbation to the equilibrium. It is proposed to use a smaller gun for spheromak formation and a large, efficient gun for sustainment. The theoretical basis for the experiment is developed, and the details of the experiment are described. A prediction of the equilibrium magnetic flux surfaces using the EFIT code is presented. 28 refs., 3 figs., 1 tab

Recent advances in high-brightness electron guns at AES

International Nuclear Information System (INIS)

Bluem, H.; Todd, A.M.M.; Cole, M.D.; Rathke, J.; Schultheiss, T.

2003-01-01

We describe a number of active Advanced Energy Systems projects pertaining to the development of advanced, high-brightness electron guns for various applications. These projects include a fully superconducting, CW RF gun, nearing test, that utilizes the niobium surface as the photocathode material. An integrated 100 mA, low emittance DC/SRF gun, ideal as an injector for ERL-type light sources and intended as the injector for a 100 kW FEL, is in late design stage. A parallel high-power, CW, normal-conducting L-band RF gun project has just begun. The early performance analysis for this gun also shows good promise as an injector for ERL-type light sources. Lastly, a fully axisymmetric RF gun, operating in X-band, is being studied as a source of extremely bright electron bunches

Particle transport and gas feed during gun injection

International Nuclear Information System (INIS)

Fowler, T K.

1999-01-01

It is shown that ion and neutral transport during gun injection tends to equalize the density in the spheromak to that in the open-line current channel. Since a gun operating at or near the ion saturation current requires a minimum density, because of transport these gun requirements also determine a minimum density in the spheromak that increases as the field increases. Hence attaining high fields by gun injection sets lower limits on the density, which in turn limits the temperature of the plasma and increases its ohmic resistance. Estimates of these effects are given using 0-D models calibrated to CTX, as guidance to 2-D UEDGE calculations in progress. For gun power levels in SSPX and the Pulsed Spheromak reactor, we find that buildup persists to the highest field levels of interest

Study on Cr(VI) Leaching from Cement and Cement Composites

Science.gov (United States)

Palascakova, Lenka; Kanuchova, Maria

2018-01-01

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time. PMID:29690550

Stereotactic breast biopsy with a biopsy gun

International Nuclear Information System (INIS)

Parker, S.H.; Lovin, J.; Luethke, J.; Jobe, W.E.; Hopper, K.D.; Yakes, W.F.

1989-01-01

With the recent introduction of stereotactic mammographic localizing devices, the authors have been performing histologic core needle breast biopsies in which the Bard biopsy gun is used in conjunction with sterotactic guidance. The authors have performed 60 breast gun biopsies with 16-gauge and 18-gauge biopsy-cut needles. These biopsies were followed immediately by traditional surgical excision. Pathologic results correlated well in 52 of the 60 patients, including 10 of 13 cancers. Three of the eight negative correlations occurred when diagnosis was made on gun biopsy but not on surgical biopsy. The stereotactic- guided gun biopsies appear to approach the surgical gold standard, decrease patient discomfort and potential disfigurement, lower the cost of breast biopsy, and lower the threshold necessary to perform breast biopsy

RF Electron Gun with Driven Plasma Cathode

CERN Document Server

Khodak, Igor

2005-01-01

It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

Lasers for RF guns: Proceedings

International Nuclear Information System (INIS)

Srinivasan-Rao, T.

1994-01-01

In the past decade, laser driven RF guns have matured from a device under development to a proven source for high brightness and low emittance electron beams. The reliability of the electron beam from these sources is dictated by the laser system that drives it. In addition, capabilities of the laser systems play a vital role in the design of the electron source for future machines such as the TESLA and NLC. The purpose of this workshop was to provide a forum for discussing the design criteria for the laser systems so that the reliability of the existing sources could be improved and the future machines could be serviced. The Workshop brought together experts in RF Guns, accelerators, and lasers, from both the commercial and academic community. Most of the presentations, discussions and conclusions at the workshop are included in these proceedings. The contents are divided into three sections, Section I contains the invited talks that outline the requirements of the RF Guns and the capabilities of the laser systems to meet these requirements. Section II includes most of the papers presented in the poster session. These papers describe various laser systems used with electron guns, schemes to modify the laser beam profile to optimize the electron bunch, and computer simulations of electron trajectories. Section III contains the summaries of the working groups. As the summary section indicates, with sufficient feed back systems, the electron gun could be made to operate reliably with minimum downtime, using commercial lasers currently available. The design of laser systems for future colliders depend critically on the choice of the cathode m the gun and its efficiency. Tentative designs of laser systems for the TESLA test facility and LCLS had been drawn assuming a copper cathode. Using a more efficient cathode will ease the energy requirement of the laser and simplify the design. The individual papers have been cataloged separately elsewhere

College Students Opinions on Gun Violence.

Science.gov (United States)

Lewis, Rhonda K; LoCurto, Jamie; Brown, Kyrah; Stowell, David; Maryman, J'Vonnah; Dean, Amber; McNair, Thoi; Ojeda, Debbie; Siwierka, Julia

2016-06-01

Gun violence and control issues have become serious public health problems. This study gathered the opinions from 419 college students from a Midwestern University. Participants were asked about beliefs about purchasing assault weapons, beliefs about bringing handguns to college campuses and beliefs about contributing factors that lead to gun violence. Participants completed surveys online. The findings showed that overall 54 % of respondents believed that military assault weapons should be banned and 53 % agree that teachers should be allowed to carry a registered handgun on campus. There were statistically significant differences between males and females on these issues. For instance, females believed military assault weapons and high capacity magazines should be banned more than 1.9 times (p = .004) p gun violence were decline in parenting and family values (17 %), gang involvement (14 %), bullying (13.8 %) and guns being easy to obtain (13.8 %). Limitations and implications for policy work are discussed.

rf traveling-wave electron gun for photoinjectors

Science.gov (United States)

Schaer, Mattia; Citterio, Alessandro; Craievich, Paolo; Reiche, Sven; Stingelin, Lukas; Zennaro, Riccardo

2016-07-01

The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL) machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least) double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

Science.gov (United States)

Gupta, Rakesh Kumar; Gupta, Vinay; Gupta, Navdeep

2012-01-01

Background: Dynamic hip screw (DHS) has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA) has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients) with an average age of 72 years (60 – 94 years) of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31), good (score 24 – 31), fair (score 16 – 23), and poor (score < 16). Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 – 16 weeks). At an average followup of 18 months (range 12 – 24 months), no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN) or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears to be an

Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

Directory of Open Access Journals (Sweden)

Rakesh Kumar Gupta

2012-01-01

Full Text Available Background: Dynamic hip screw (DHS has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients with an average age of 72 years (60 − 94 years of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31, good (score 24 − 31, fair (score 16 − 23, and poor (score < 16. Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 − 16 weeks. At an average followup of 18 months (range 12 − 24 months, no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears

Durability of pulp fiber-cement composites

Science.gov (United States)

Mohr, Benjamin J.

Wood pulp fibers are a unique reinforcing material as they are non-hazardous, renewable, and readily available at relatively low cost compared to other commercially available fibers. Today, pulp fiber-cement composites can be found in products such as extruded non-pressure pipes and non-structural building materials, mainly thin-sheet products. Although natural fibers have been used historically to reinforce various building materials, little scientific effort has been devoted to the examination of natural fibers to reinforce engineering materials until recently. The need for this type of fundamental research has been emphasized by widespread awareness of moisture-related failures of some engineered materials; these failures have led to the filing of national- and state-level class action lawsuits against several manufacturers. Thus, if pulp fiber-cement composites are to be used for exterior structural applications, the effects of cyclical wet/dry (rain/heat) exposure on performance must be known. Pulp fiber-cement composites have been tested in flexure to examine the progression of strength and toughness degradation. Based on scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), energy dispersive spectroscopy (EDS), a three-part model describing the mechanisms of progressive degradation has been proposed: (1) initial fiber-cement/fiber interlayer debonding, (2) reprecipitation of crystalline and amorphous ettringite within the void space at the former fiber-cement interface, and (3) fiber embrittlement due to reprecipitation of calcium hydroxide filling the spaces within the fiber cell wall structure. Finally, as a means to mitigate kraft pulp fiber-cement composite degradation, the effects of partial portland cement replacement with various supplementary cementitious materials (SCMs) has been investigated for their effect on mitigating kraft pulp fiber-cement composite mechanical property degradation (i.e., strength and toughness

HIGH VELOCITY THERMAL GUN FOR SURFACE PREPARATION AND TREATMENT

Directory of Open Access Journals (Sweden)

I.A. Gorlach

2012-01-01

Full Text Available Many surface preparation and treatment processes utilise compressed air to propel particles against surfaces in order to clean and treat them. The effectiveness of the processes depends on the velocity of the particles, which in turn depends on the pressure of the compressed air. This paper describes a thermal gun built on the principles of High Velocity Air Fuel (HVAF and High Velocity Oxy Fuel (HVOF processes. The designed apparatus can be used for abrasive blasting, coating of surfaces, cutting of rocks, removing rubber from mining equipment, cleaning of contaminations etc.

Strong gun laws are not enough: the need for improved enforcement of secondhand gun transfer laws in Massachusetts.

Science.gov (United States)

Braga, Anthony A; Hureau, David M

2015-10-01

Research suggests that an overwhelming majority of crime guns were transferred by private sellers before recovery by law enforcement. Unfortunately, most states do not regulate these transactions. This study examines whether analyses of state-level private transfer data could be used to develop interventions to reduce the supply of handguns to violent criminals. Traced Boston crime handguns first sold at Massachusetts license dealers were matched to state secondhand gun transfer data. Logistic regression and descriptive statistics were used to analyze the characteristics of recovered crime guns and in-state primary and secondary market transaction patterns. For crime handguns with records of secondary market transactions in Massachusetts, many rapidly move from private transfer to recovery by the police. Unfortunately, important transaction data on the in-state sources of nearly 63% of recovered handguns were not readily available to law enforcement agencies. Data on private transfers of guns could be used to prevent violent injuries by reducing criminal access. However, the passage of strong private transfer gun laws needs to be accompanied by investments in the vigorous enforcement of reporting requirements. Copyright © 2015 Elsevier Inc. All rights reserved.

Cement-in-cement acetabular revision with a constrained tripolar component.

Science.gov (United States)

Leonidou, Andreas; Pagkalos, Joseph; Luscombe, Jonathan

2012-02-17

Dislocation of a total hip replacement (THR) is common following total hip arthroplasty (THA). When nonoperative management fails to maintain reduction, revision surgery is considered. The use of constrained acetabular liners has been extensively described. Complete removal of the old cement mantle during revision THA can be challenging and is associated with significant complications. Cement-in-cement revision is an established technique. However, the available clinical and experimental studies focus on femoral stem revision. The purpose of this study was to present a case of cement-in-cement acetabular revision with a constrained component for recurrent dislocations and to investigate the current best evidence for this technique. This article describes the case of a 74-year-old woman who underwent revision of a Charnley THR for recurrent low-energy dislocations. A tripolar constrained acetabular component was cemented over the primary cement mantle following removal of the original liner by reaming, roughening the surface, and thoroughly irrigating and drying the primary cement. Clinical and radiological results were good, with the Oxford Hip Score improving from 11 preoperatively to 24 at 6 months postoperatively. The good short-term results of this case and the current clinical and biomechanical data encourage the use of the cement-in-cement technique for acetabular revision. Careful irrigation, drying, and roughening of the primary surface are necessary. Copyright 2012, SLACK Incorporated.

ULTRA-LIGHTWEIGHT CEMENT

International Nuclear Information System (INIS)

Fred Sabins

2001-01-01

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job

The Development of the Linac Coherent Light Source RF Gun

International Nuclear Information System (INIS)

Dowell, D

2008-01-01

The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron laser (FEL) requiring extraordinary beam quality to saturate at 1.5 angstroms within a 100 meter undulator.[1] This new type of light source is using the last kilometer of the three kilometer linac at SLAC to accelerate the beam to an energy as high as 13.6 GeV and required a new electron gun and injector to produce a very bright beam for acceleration. At the outset of the project it was recognized that existing RF guns had the potential to produce the desired beam but none had demonstrated it. Therefore a new RF gun or at least the modification of an existing gun was necessary. The parameters listed in Table 1 illustrate the unique characteristics of LCLS which drive the requirements for the electron gun as given in Table 2. The gun beam quality needs to accommodate emittance growth as the beam is travels through approximately one kilometer of linac and two bunch compressors before reaching the undulator. These beam requirements were demonstrated during the recent commissioning runs of the LCLS injector and linac [2] due to the successful design, fabrication, testing and operation of the LCLS gun. The goal of this paper is to relate the technical background of how the gun was able to achieve and in some cases exceed these requirements by understanding and correcting the deficiencies of the prototype s-band RF photocathode gun, the BNL/SLAC/UCLA Gun III. This paper begins with a brief history and technical description of Gun III and the Gun Test Facility (GTF) at SLAC, and studies of the gun's RF and emittance compensation solenoid. The work at the GTF identified the gun and solenoid deficiencies, and helped to define the specifications for the LCLS gun. Section 1.1.5 describes the modeling used to compute and correct the gun RF fields and Section 1.1.6 describes the use of these fields in the electron beam simulations. The magnetic design and measurements of

Gun Carrying by High School Students in Boston, MA: Does Overestimation of Peer Gun Carrying Matter?

Science.gov (United States)

Hemenway, David; Vriniotis, Mary; Johnson, Renee M.; Miller, Matthew; Azrael, Deborah

2011-01-01

This paper investigates: (1) whether high school students overestimate gun carrying by their peers, and (2) whether those students who overestimate peer gun carrying are more likely to carry firearms. Data come from a randomly sampled survey conducted in 2008 of over 1700 high school students in Boston, MA. Over 5% of students reported carrying a…

The Influence of the Axial Magnetic Field Upon- the Coaxial Plasma Gun Parameters

International Nuclear Information System (INIS)

El-Aragi, G.M.; El-Demardash, A.

2001-01-01

This study concerns with the influence of an applied axial magnetic field upon the electrical parameters and on the brightness (luminance) of argon plasma. The brightness was measured by with a photomultiplier type of IP28 RCA. The experimental results are investigated with plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied. It was found that the thickness of skin-layer δ about 0.01 cm and the wavelength λ, of the perturbation about 1.3 cm i.e. the instability has been satisfied. The growth rate γ of the instability about 10 6 sec -1 . (author)

The PLX- α Plasma Guns: Progress and Plans

Science.gov (United States)

Witherspoon, F. D.; Brockington, S.; Case, A.; Cruz, E.; Luna, M.; Thio, Y. C. Francis; LANL PLX-α Team

2017-10-01

The ALPHA coaxial plasma guns are being developed to support a 60-gun scaling study of spherically imploding plasma liners as a standoff driver for plasma-jet-driven magneto-inertial fusion (PJMIF). Seven complete guns have been delivered to LANL with 6 guns currently undergoing simultaneous test firings on PLX. The guns are designed to operate over a range of parameters: 0.5-5.0 mg of Ar, Ne, N2, Kr, and Xe; 20-60 km/s; 2 × 1016 cm-3 muzzle density; and up to 7.5 kJ stored energy per gun. Each coaxial gun incorporates a fast dense gas injection and triggering system, a compact low-weight pfn with integral sparkgap switching, and a contoured coaxial gap to suppress the blow-by instability. Optimizing parameter scans performed at HyperV have achieved : 4 mg at >50 km/s and length of 10 cm. Peak axial density 30 cm from the muzzle is 2 ×1016 cm-3. We will provide an overview of the experimental results, along with plans for further improvements in reliability, maintainability, fabricability, and plasma jet performance, with the latter focused on further improvements in the fast gas valve and the ignitors. This work supported by the ARPA-E ALPHA Program under contract DE-AR0000566 and Strong Atomics, LLC.

Advances in DC photocathode electron guns

International Nuclear Information System (INIS)

Dunham, B.M.; Hartmann, P.; Kazimi, R.; Liu, H.; Poelker, B.M.; Price, J.S.; Rutt, P.M.; Schneider, W.J.; Sinclair, C.K.

1999-01-01

At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughput. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion backbombardment, and precise control of all of the electrons emitted from the cathode. In this paper, we will review recent results and discuss implications for future photocathode guns. copyright 1999 American Institute of Physics

The polarized electron gun for the SLC

International Nuclear Information System (INIS)

Schultz, D.C.; Clendenin, J.; Frisch, J.; Hoyt, E.; Klaisner, L.; Woods, M.; Wright, D.; Zolotorev, M.

1992-03-01

A new polarized electron gun for use on the SLC at SLAC has been built and tested. It is a diode gun with a laser driven GaAs photocathode. It is designed to provide short (2ns) pulses of 10 A at 160 kV at 120 Hz. The design features of the gun and results from a testing program on a new and dedicated beam line are presented. Early results from operation on the SLC will also be shown

Cement Formation

DEFF Research Database (Denmark)

Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

2012-01-01

Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

Tri-Service Green Gun Barrel (PP 1074)

National Research Council Canada - National Science Library

Rusch, Lawrence F

2003-01-01

...) PP 1074 Tri-Service Green Gun Barrel. The program's goal was to develop an environmentally friendly process for depositing wear and erosion resistant materials onto gun bores replacing the current hazardous aqueous electro-deposition...

Progress on a cryogenically cooled RF gun polarized electron source

Energy Technology Data Exchange (ETDEWEB)

Fliller, R.P., III; Edwards, H.; /Fermilab

2006-08-01

RF guns have proven useful in multiple accelerator applications. An RF gun capable of producing polarized electrons is an attractive electron source for the ILC or an electron-ion collider. Producing such a gun has proven elusive. The NEA GaAs photocathode needed for polarized electron production is damaged by the vacuum environment in an RF gun. Electron and ion back bombardment can also damage the cathode. These problems must be mitigated before producing an RF gun polarized electron source. In this paper we report continuing efforts to improve the vacuum environment in a normal conducting RF gun by cooling it with liquid nitrogen after a high temperature vacuum bake out. We also report on a design of a cathode preparation chamber to produce bulk GaAs photocathodes for testing in such a gun. Future directions are also discussed.

Stability and performance studies of the PITZ photoelectron gun

Energy Technology Data Exchange (ETDEWEB)

Isaev, Igor

2018-02-15

The invention of free electron lasers (FELs) opened new opportunities for the investigation of natural phenomena. However, the operation of a FEL requires high energy, high peak current electron beams with very small transverse emittance which causes extreme requirements for the corresponding electron sources. Besides the high beam quality, the electron sources must have very high operational stability and reliability. One of the electron source types which satisfy FEL requirements is a photoelectron gun. Photoelectron guns combine photoemissive electron generation and direct acceleration in a Radio Frequency (RF) cavity. The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was established as a test stand of the electron source for FELs like FLASH and the European XFEL in Hamburg. The studies of the beam emittance at PITZ showed that the gun is able to produce electron beams with emittance even smaller than it is required by XFEL specifications. But the experiments on the emittance revealed discrepancies between expected gun behavior and observation, such as the difference in optimal parameters for the smallest emittance value, asymmetry of the transverse beam profile and the phase spaces. The work performed at PITZ includes preparation of several RF guns for their subsequent operation at FLASH and the European XFEL. RF conditioning of a gun cavity is one of the major steps of the preparation of a high brightness electron source required for modern FELs. A thorough procedure is applied to increase the peak and average RF power in the gun cavity, including an increase of the repetition rate and RF pulse length combined with a gun solenoid current sweep. The main goals of this thesis are: (1) an attempt of deep understanding of physical processes taking place during operation of a photoelectron gun (conditioning process, parameters adjustments); (2) definition of operational problems sources and explanation of the experimentally obtained results in the gun

Stability and performance studies of the PITZ photoelectron gun

International Nuclear Information System (INIS)

Isaev, Igor

2018-02-01

The invention of free electron lasers (FELs) opened new opportunities for the investigation of natural phenomena. However, the operation of a FEL requires high energy, high peak current electron beams with very small transverse emittance which causes extreme requirements for the corresponding electron sources. Besides the high beam quality, the electron sources must have very high operational stability and reliability. One of the electron source types which satisfy FEL requirements is a photoelectron gun. Photoelectron guns combine photoemissive electron generation and direct acceleration in a Radio Frequency (RF) cavity. The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was established as a test stand of the electron source for FELs like FLASH and the European XFEL in Hamburg. The studies of the beam emittance at PITZ showed that the gun is able to produce electron beams with emittance even smaller than it is required by XFEL specifications. But the experiments on the emittance revealed discrepancies between expected gun behavior and observation, such as the difference in optimal parameters for the smallest emittance value, asymmetry of the transverse beam profile and the phase spaces. The work performed at PITZ includes preparation of several RF guns for their subsequent operation at FLASH and the European XFEL. RF conditioning of a gun cavity is one of the major steps of the preparation of a high brightness electron source required for modern FELs. A thorough procedure is applied to increase the peak and average RF power in the gun cavity, including an increase of the repetition rate and RF pulse length combined with a gun solenoid current sweep. The main goals of this thesis are: (1) an attempt of deep understanding of physical processes taking place during operation of a photoelectron gun (conditioning process, parameters adjustments); (2) definition of operational problems sources and explanation of the experimentally obtained results in the gun

The design of gridded pierce guns for accelerators

International Nuclear Information System (INIS)

True, R.

1985-01-01

It is vital to employ ultra-laminar beams in electron linacs to maximize charge transport to the target. This paper presents numerical and experimental design techniques which have led to significant improvements in gridded Pierce guns used in microwave tubes and electron linacs. The paper concludes with two gun/injector concepts which have demonstrated enhanced performance over standard triode Pierce guns

Study of the electrical signals observed during the initial stage in a coaxial gun

International Nuclear Information System (INIS)

Moreno, C.; Vieytes, R.

1995-01-01

In this work high frequency oscillations further experimental data, along with its theoretical modeling will be given for initial phase in a coaxial gun constructed to be used in technological applications of plasma. Particular attention was devoted to find any dependence between the measured frequencies and the operating pressure and voltage. 1 ref., 1 fig., 1 tab

The importance of pulsed lavage on interface temperature and ligament tension force in cemented unicompartmental knee arthroplasty.

Science.gov (United States)

Clarius, M; Seeger, J B; Jaeger, S; Mohr, G; Bitsch, R G

2012-05-01

Mechanical loosening is the most common cause of revision in unicompartmental knee arthroplasty. We determined the effect of bone lavage on tibial cement penetration and interface temperature with controlled ligament tension forces. We presumed pulsed lavage would allow increased cement penetration compared with syringe lavage. Cemented unicompartmental knee arthroplasty was performed in 12 pairs of fresh-frozen knees. Lavage was performed using pulsed lavage on one side (A) and syringe lavage on the other (B). Cement penetration pressure, interface temperature, and ligament tension forces were continuously monitored during the operation. Screened radiographs were taken and cement penetration under the tibial plateau was measured. The pulsed lavage group showed a mean cement penetration area of 187.24 (SD 36.37) mm², whereas 144.29 (SD 35.74) mm(2) was measured in the group with syringe lavage. Cement penetration pressure was 13.29 (SD 8.69) kPa in Group A and 20.21 (SD 7.78) kPa in Group B. Maximum interface temperatures of 46.99°C were observed in Group A and 45.02°C in Group B. Our data showed pulsed lavage cleansing of the cancellous tibial bone substantially improved cement penetration compared with syringe lavage without reaching the temperature threshold for bone necrosis. We recommend the routine use of pulsed lavage to improve long-term fixation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Plasma-gun fueling for tokamak reactors

International Nuclear Information System (INIS)

Ehst, D.A.

1980-11-01

In light of the uncertain extrapolation of gas puffing for reactor fueling and certain limitations to pellet injection, the snowplow plasma gun has been studied as a fueling device. Based on current understanding of gun and plasma behavior a design is proposed, and its performance is predicted in a tokamak reactor environment

Therminoic gun control system for the CEBAF injector

International Nuclear Information System (INIS)

Pico, R.; Diamond, B.; Fugitt, J.; Bork, R.

1989-01-01

The injector for the CEBAF accelerator must produce a high-quality electron beam to meet the overall accelerator specifications. A Hermosa electron gun with a 2 mm-diameter cathode and a control aperture has been chosen as the electron source. This must be controlled over a wide range of operating conditions to meet the beam specifications and to provide flexibility for accelerator commissioning. The gun is controlled using Computer Automated Measurement and Control (CAMAC IEEE-583) technology. The system employs the CAMAC-based control architecture developed at CEBAF. The control system has been tested, and early operating data on the electron gun and the injector beam transport system has been obtained. This system also allows gun parameters to be stored at the operator location, without paralyzing operation. This paper describes the use of this computer system in the control of the CEBAF electron gun. 2 refs., 6 figs., 1 tab

An rf modulated electron gun pulser for linacs

International Nuclear Information System (INIS)

Legg, R.; Hartline, R.

1991-01-01

Present linac injector designs often make use of sub-harmonic prebuncher cavities to properly bunch the electron beam before injection into a buncher and subsequent accelerating cavities. This paper proposes an rf modulated thermionic gun which would allow the sub-harmonic buncher to be eliminated from the injector. The performance parameters for the proposed gun are 120 kV operating voltage, macropulse duration-single pulse mode 2 nsec, multiple pulse mode 100 nsec, rf modularing frequency 500 MHz, charge per micropulse 0.4 nC, macropulse repetition frequency 10 Hz (max). The gun pulser uses a grid modulated planar triode to drive the gun cathode. The grid driver takes advantage of recently developed modular CATV rf drivers, high performance solid state pulser devices, and high-frequency fiber optic transmitters for telecommunications. Design details are presented with associated SPICE runs simulating operation of the gun

A Twofold Comparison between Dual Cure Resin Modified Cement and Glass Ionomer Cement for Orthodontic Band Cementation.

Science.gov (United States)

Attar, Hanaa El; Elhiny, Omnia; Salem, Ghada; Abdelrahman, Ahmed; Attia, Mazen

2016-12-15

To test the solubility of dual cure resin modified resin cement in a food simulating solution and the shear bond strength compared to conventional Glass ionomer cement. The materials tested were self-adhesive dual cure resin modified cement and Glass Ionomer (GIC). Twenty Teflon moulds were divided into two groups of tens. The first group was injected and packed with the modified resin cement, the second group was packed with GIC. To test the solubility, each mould was weighed before and after being placed in an analytical reagent for 30 days. The solubility was measured as the difference between the initial and final drying mass. To measure the Shear bond strength, 20 freshly extracted wisdom teeth were equally divided into two groups and embedded in self-cure acrylic resin. Four mm sections of stainless steel bands were cemented to the exposed buccal surfaces of teeth under a constant load of 500 g. Shear bond strength was measured using a computer controlled materials testing machine and the load required to deband the samples was recorded in Newtons. GIC showed significantly higher mean weight loss and an insignificant lower Shear bond strength, compared to dual cure resin Cement. It was found that dual cure resin modified cement was less soluble than glass ionomer cement and of comparable bond strength rendering it more useful clinically for orthodontic band cementation.

Gun violence in Americans' social network during their lifetime.

Science.gov (United States)

Kalesan, Bindu; Weinberg, Janice; Galea, Sandro

2016-12-01

The overall burden of gun violence death and injury in the US is now well understood. However, no study has shown the extent to which gun violence is associated with the individual lives of Americans. We used fatal and non-fatal gun injury rates in 2013 from Centers for Disease Control and Prevention's Web-based Injury Statistics Query and Reporting System (WISQARS) and generally accepted estimates about the size of an American's social network to determine the likelihood that any given person will know someone in their personal social network who is a victim of gun violence during their lifetime. We derived estimates in the overall population and among racial/ethnic groups and by gun-injury intent. The likelihood of knowing a gun violence victim within any given personal network over a lifetime is 99.85% (99.8% to 99.9%). The likelihood among non-Hispanic white, black, Hispanic and other race Americans were 97.1%, 99.9%, 99.5% and 88.9% respectively. Nearly all Americans of all racial/ethnic groups are likely to know a victim of gun violence in their social network during their lifetime. Copyright © 2016 Elsevier Inc. All rights reserved.

The mechanical effect of the existing cement mantle on the in-cement femoral revision.

LENUS (Irish Health Repository)

Keeling, Parnell

2012-08-01

Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct.

XRF analysis of portland cement for major and trace elements

International Nuclear Information System (INIS)

Abdunnabi, A. R.

2012-12-01

Libyan portland cement produced in several factories around the country, in Lip tis, Zoltan, Souq-Elkamis, Dernah and El-Fatach, were analyzed for quantitative major and trace elements and mineral content, which were compered with those imported from Spain, Romania, Cyprus, and Egypt. X-ray fluorescence spectro X lab 2000 spectrometer equipped with Rh-and X-ray tube was used for the analysis of various samples. The detector Si(Li) with a resolution of 148 eV at Mn K-a=5.9 keV facilitates the determination of a wide range of elements from sodium to uranium, with a detection limit at sub levels. Cement samples in the powder form were analyzed using the pellet-technique. The pellets were prepared by mixing 4g of the cement powder with 0.9 g of binder (HWC) and pressed at high pressure. A ful analysis including, background counting, matrix correction and all relevant corrections were achieved automatically by XLAB 2000 software package. For major and trace elements X RF results were higher for most of the elements than those analyzed with atomic absorption spectrometry. The mineral content showed that Libyan cement is comparable to the imported ones, also the Libyan cement meets the requirements of the international specifications of the portland cement. (Author)

Perancangan Sistem Kontrol PID Untuk Pengendali Sumbu Elevasi Gun Pada Turret-Gun Kaliber 20 Milimeter

Directory of Open Access Journals (Sweden)

Dimas Kunto Ariwibowo

2017-01-01

Full Text Available Pertahanan negara pada hakikatnya adalah segala upaya pertahanan yang bersifat semesta yang didasarkan pada kesadaran atas hak dan kewajiban warga negara serta keyakinan pada kekuatan sendiri dengan tujuan untuk menjaga dan melindungi kedaulatan negara, keutuhan wilayah NKRI dan keselamatan segenap bangsa. Salah satu alat pendukung pertahanan yaitu senjata laras panjang, Turret-Gun.  Adapun langkah-langkah yang dilakukan dalam merancang pengendali PID Turret-Gun kaliber 20mm ini diawali dengan studi literatur serta studi lapangan mengenai mekanisme dan parameter-parameter yang terdapat pada Turret-Gun pada sumbu elevasi. Setelah itu dilakukan perancangan transmisi dan sistem kontrol Turret-Gun untuk dievaluasi grafik responnya yang akan digunakan sebagai acuan untuk merancang pengendali PID yang sesuai. Selanjutnya pengendali PID yang telah dirancang lalu disimulasikan, sehingga menghasilkan grafik respon yang sesuai dengan kriteria yang dibutuhkan. Hasil yang telah didapatkan dari penelitian ini adalah konstanta PID yang direkomendasikan untuk , , dan secara berturut-turut adalah sebesar 23061.024, 37820.07 dan 3515.4 yang menghasilkan transient response dengan nilai overshoot sebesar 19.9 % , steady state error sebesar 0 % serta settling time sebesar 0.935 detik. Hasil analisa kestabilan untuk sistem kontrol dengan konstanta PID tersebut menunjukkan bahwa sistem kontrol telah stabil, baik menggunakan metode Root Locus maupun metode Routh-Hurwitz.

rf traveling-wave electron gun for photoinjectors

Directory of Open Access Journals (Sweden)

Mattia Schaer

2016-07-01

Full Text Available The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

Evaluation of Smart Gun Technologies preliminary report

Energy Technology Data Exchange (ETDEWEB)

Weiss, D.R.

1996-01-01

The Smart Gun Technology Project has a goal to eliminate the capability of an unauthorized user from firing a law enforcement officer`s firearm by implementing {open_quote}smart{close_quote} technologies. Smart technologies are those that can in some manner identify an officer. This report will identify, describe, and grade various technologies as compared to the requirements that were obtained from officers. This report does not make a final recommendation for a smart gun technology, nor does it give the complete design of a smart gun system.

Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

Directory of Open Access Journals (Sweden)

Valery A. Tutyk

2013-01-01

Full Text Available The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum gas-discharge electron gun is revealed. It causes an avalanche increase of electron beam current and burning of plasma-beam discharge in the whole space of the vacuum chamber volume and generation of electromagnetic radiation is revealed. Achieved results will be used for implementation of various vacuum technologies in the medium of reaction gas and generated electromagnetic radiation.

Gun utopias? Firearm access and ownership in Israel and Switzerland.

Science.gov (United States)

Rosenbaum, Janet E

2012-02-01

The 2011 attempted assassination of a US representative renewed the national gun control debate. Gun advocates claim mass-casualty events are mitigated and deterred with three policies: (a) permissive gun laws, (b) widespread gun ownership, (c) and encouragement of armed civilians who can intercept shooters. They cite Switzerland and Israel as exemplars. We evaluate these claims with analysis of International Crime Victimization Survey (ICVS) data and translation of laws and original source material. Swiss and Israeli laws limit firearm ownership and require permit renewal one to four times annually. ICVS analysis finds the United States has more firearms per capita and per household than either country. Switzerland and Israel curtail off-duty soldiers' firearm access to prevent firearm deaths. Suicide among soldiers decreased by 40 per cent after the Israeli army's 2006 reforms. Compared with the United States, Switzerland and Israel have lower gun ownership and stricter gun laws, and their policies discourage personal gun ownership.

A tapered multi-gap multi-aperture pseudospark-sourced electron gun based X-band slow wave oscillator

Science.gov (United States)

Kumar, N.; Lamba, R. P.; Hossain, A. M.; Pal, U. N.; Phelps, A. D. R.; Prakash, R.

2017-11-01

The experimental study of a tapered, multi-gap, multi-aperture pseudospark-sourced electron gun based X-band plasma assisted slow wave oscillator is presented. The designed electron gun is based on the pseudospark discharge concept and has been used to generate a high current density and high energy electron beam simultaneously. The distribution of apertures has been arranged such that the field penetration potency inside the backspace of the hollow-cathode is different while passing through the tapered gap region. This leads to non-concurrent ignition of the discharge through all the channels which is, in general, quite challenging in the case of multi-aperture plasma cathode electron gun geometries. Multiple and successive hollow cathode phases are reported from this electron gun geometry, which have been confirmed using simulations. This geometry also has led to the achievement of ˜71% fill factor inside the slow wave oscillator for an electron beam of energy of 20 keV and a beam current density in the range of 115-190 A/cm2 at a working argon gas pressure of 18 Pa. The oscillator has generated broadband microwave output in the frequency range of 10-11.7 GHz with a peak power of ˜10 kW for ˜50 ns.

Thermodynamic and structural characteristics of cement minerals at elevated temperature

International Nuclear Information System (INIS)

Bruton, C.J.; Meike, A.; Viani, B.E.; Martin, S.; Phillips, B.L.

1994-05-01

We have instituted an experimental and including program designed to elucidate the structural and thermodynamic response of cement minerals to elevated temperature. Components of the program involve: (a) synthesis of hydrated Ca-silicates; (b) structural analysis of cement phases induced by heating and dehydration/rehydration; (c) mechanistic and thermodynamic descriptions of the hydration/dehydration behavior of hydrated Ca-silicates as a function of temperature, pressure and relative humidity; (d) study of naturally occurring hydrated Ca-silicates; and (e) measurements of thermodynamic data for hydrated Ca-silicates

The electromagnetic rocket gun - a means to reach ultrahigh velocities

International Nuclear Information System (INIS)

Winterberg, F.

1983-01-01

A novel kind of electromagnetic launcher for the acceleration of multigram-size macroparticles, up to velocities required for impact fusion, is proposed. The novel launcher concept combines the efficiency of a gun with the much higher velocities attainable by a rocket. In the proposed concept a rocket-like projectile is launched inside a gun barrel, drawing its energy from a travelling magnetic wave. The travelling magnetic wave heats and ionizes the exhaust jet of the rocket. As a result, the projectile i propelled both by the recoil from the jet and the magnetic pressure of the travelling magnetic wave. In comparison to magnetic linear accelerators, accelerating either superconducting or ferromagnetic projectiles, the proposed concept has several important advantages. First, the exhaust jet is much longer than the rocket-like projectile and which permits a much longer switching time to turn on the travelling magnetic wave. Second, the proposed concept does not require superconducting projectiles, or projectiles made from expensive ferromagnetic material. Third, unlike in railgun accelerators, the projectile can be kept away from the wall, and thereby can reach much larger velocities. (orig.)

Gun Dynamics Laboratory

Data.gov (United States)

Federal Laboratory Consortium — The Gun Dynamics Laboratory is a research multi-task facility, which includes two firing bays, a high bay area and a second floor laboratory space. The high bay area...

Evaluation of the amount of excess cement around the margins of cement-retained dental implant restorations: the effect of the cement application method.

Science.gov (United States)

Chee, Winston W L; Duncan, Jesse; Afshar, Manijeh; Moshaverinia, Alireza

2013-04-01

Complete removal of excess cement from subgingival margins after cementation of implant-supported restorations has been shown to be unpredictable. Remaining cement has been shown to be associated with periimplant inflammation and bleeding. The purpose of this study was to investigate and compare the amount of excess cement after cementation with 4 different methods of cement application for cement-retained implant-supported restorations. Ten implant replicas/abutments (3i) were embedded in acrylic resin blocks. Forty complete veneer crowns (CVCs) were fabricated by waxing onto the corresponding plastic waxing sleeves. The wax patterns were cast and the crowns were cemented to the implant replicas with either an interim (Temp Bond) or a definitive luting agent (FujiCEM). Four methods of cement application were used for cementation: Group IM-Cement applied on the internal marginal area of the crown only; Group AH-Cement applied on the apical half of the axial walls of the crown; Group AA-Cement applied to all axial walls of the interior surface of the crown, excluding the occlusal surface; and Group PI-Crown filled with cement then seated on a putty index formed to the internal configuration of the restoration (cementation device) (n=10). Cement on the external surfaces was removed before seating the restoration. Cement layers were applied on each crown, after which the crown was seated under constant load (80 N) for 10 minutes. The excess cement from each specimen was collected and measured. One operator performed all the procedures. Results for the groups were compared, with 1 and 2-way ANOVA and the Tukey multiple range test (α=.05). No significant difference in the amount of excess/used cement was observed between the 2 different types of cements (P=.1). Group PI showed the least amount of excess cement in comparison to other test groups (P=.031). No significant difference was found in the amount of excess cement among groups MI, AH, and AA. Group AA showed the

A high voltage test stand for electron gun qualification for LINACs

International Nuclear Information System (INIS)

Wanmode, Yashwant D.; Mulchandani, J.; Acharya, M.; Bhisikar, A.; Singh, H.G.; Shrivastava, Purushottam

2011-01-01

An electron gun lest stand has been developed at RRCAT. The test stand consists of a high voltage pulsed power supply, electron gun filament supply, grid supply, UHV system and electron gun current measurement system. Several electron guns developed indigenously were evaluated on this test stand. The shielding is provided for the electron gun set up. Electron gun tests can be tested upto 55 kV with pulse width of 15 microsecs and pulse repetition rates up to 200 Hz. The technical details of the subsystems are furnished and results of performance of the test stand have been reported in this paper. (author)

76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

Science.gov (United States)

2011-12-08

... and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the subject... duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... and Cement Clinker from Japan: Investigation No. 731- TA-461 (Third Review). By order of the...

Gun barrel erosion - Comparison of conventional and LOVA gun propellants

NARCIS (Netherlands)

Hordijk, A.C.; Leurs, O.

2006-01-01

The research department Energetic Materials within TNO Defence, Security and Safety is involved in the development and (safety and insensitive munitions) testing of conventional (nitro cellulose based) and thermoplastic elastomer (TPE) based gun propellants. Recently our testing capabilities have

Engineering design of the PLX- α coaxial gun

Science.gov (United States)

Cruz, E.; Brockington, S.; Case, A.; Luna, M.; Witherspoon, F. D.; Thio, Y. C. Francis; PLX-α Team

2017-10-01

We describe the engineering and technical improvements, as well as provide a detailed overview of the design choices, of the latest PLX- α coaxial gun designed for the 60-gun scaling study of spherically imploding plasma liners as a standoff driver for plasma-jet-driven magneto-inertial fusion. Each coaxial gun incorporates a fast, dense gas injection and triggering system, a compact low-weight pfn with integral sparkgap switching, and a contoured gap designed to suppress the blow-by instability. The evolution of the latest Alpha gun is presented with emphasis on its upgraded performance. Changes include a faster more robust gas valve, better-quality ceramic insulator material and enhancements to overall design layout. These changes result in a gun with increased repeatability, reduced potential failure modes, improved fault tolerance and better than expected efficiency. A custom 600- μF, 5-kV pfn and a set of six inline sparkgap switches operated in parallel are mounted directly to the back of the gun, and are designed to reduce inductance, cost, and complexity, maximize efficiency and system reliability, and ensure symmetric current flow. This work supported by the ARPA-E ALPHA Program under contract DE-AR0000566 and Strong Atomics, LLC.

Spectrometer gun

Science.gov (United States)

Waechter, David A.; Wolf, Michael A.; Umbarger, C. John

1985-01-01

A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

Mass Shootings, Mental Illness, and Gun Control.

Science.gov (United States)

Philpott-Jones, Sean

2018-03-01

In the wake of the Stoneman Douglas School shooting, Republican and Democratic leaders-like the American electorate they represent-remain sharply divided in their responses to gun violence. They are united in their condemnation of these mass shootings, but they disagree about whether stricter or looser gun control laws are the answer. Those on the right side of the political aisle suggest that the issue is one of mental illness rather than gun control. Conversely, those who are more liberal or progressive in their political learnings are quick to condemn attempts to reframe the issue of mass shootings as a mental health problem. Both sides are wrong. Mass shootings are indeed partially a mental health problem, albeit one poorly addressed by our current laws and policies. But the solution to mass shootings also needs to consider strategies that may reduce gun violence in general. © 2018 The Hastings Center.

Acceleration of solid pellets using a plasma gun

International Nuclear Information System (INIS)

Buller, T.L.; Turnbull, R.J.; Kim, K.

1979-01-01

The use of solid pellets of hydrogen isotopes to refuel thermonuclear fusion reactors based on the tokamak configuration will require that the pellets be accelerated to high velocities. One possible method of acceleration is to interact a fast plasma from a plasma gun with the pellets. In this paper preliminary results are given on the acceleration of solid pellets with a plasma gun. The plasma-gun requirements for successful acceleration to high velocities are discussed

Cementing a wellbore using cementing material encapsulated in a shell

Energy Technology Data Exchange (ETDEWEB)

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Spadaccini, Christopher M.; Cowan, Kenneth Michael

2016-08-16

A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

Cementing a wellbore using cementing material encapsulated in a shell

Energy Technology Data Exchange (ETDEWEB)

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Floyd, III, William C.; Spadaccini, Christopher M.; Vericella, John J.; Cowan, Kenneth Michael

2017-03-14

A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

Cementation of Radioactive Waste from a PWR with Calcium Sulfoaluminate Cement

International Nuclear Information System (INIS)

Li, J.

2013-01-01

Spent radioactive ion-exchange resin (SIER) and evaporation concentrates are radioactive wastes that are produced at by pressurized water reactor (PWR) nuclear power stations. Borate, which is used as a retardent for cement, is also present as a moderator in a PWR, therefore, borate will be present in both ion-exchange resins and evaporation concentrates. In this study the use of Calcium sulfoaluminate cements (SAC) as encapsulation medium for these waste streams was investigated. The study involved the manufacturing of different cement test samples with different amounts of SAC cement, waste resins (50% water content) and admixtures. In order to reduce hydration heat during 200 L solidification experiments, different admixtures were investigated. Initial results based on compressive strength tests and hydration temperature studies, indicated that zeolite was the best admixture for the current waste form. Experiments indicated that the addition of resin material into the current cement matrix reduces the hydration heat during curing Experimental results indicated that a combination of SAC (35 wt. %), zeolite (7 wt. %) mix with 42 wt. % resins (50% water content) and 16 wt. % of water forms a optimum cured monolith with low hydration heat. The microstructures of hydrated OPC, SAC and SAC with zeolite addition were studied using a Scanning Electron Microscopy (SEM). SEM results indicated that the SAC matrices consist of a needle type structure that changed gradually into a flake type structure with the addition of zeolite. Additionally, the presence of zeolite material inside the SAC matrix reduced the leaching rates of radionuclides significantly. In a final 200 L grouting test, measured results indicated a hydration temperature below 90oC withno thermal cracks after solidified. The influence of radiation on the compressive strength and possible gas generation (due to radiolysis) on cement waste forms containing different concentrations ion exchange resin was

Maximizing heavy-oil recovery by containing steam through optimized cementing

Energy Technology Data Exchange (ETDEWEB)

Ravi, K.; Hunter, B.; Kulakofsky, D [Halliburton Energy Services, Calgary, AB (Canada)

2008-10-15

As the world's oil and gas reserves decline, interest in unconventional sources, such as heavy oil, is increasing in response to global energy demand. Conventional methods are not sufficient to produce highly viscous heavy oil, and measures must be taken to decrease its viscosity. Although steam injection is an option, steam heats the casing and the cement sheath posing considerable thermal stress on the casing and the cement sheath. This paper described the design procedures that are required for evaluating the properties needed in the cement sheath in order to assist in withstanding thermal stresses. The steps needed to deliver an optimized cement system were presented. The paper presented an illustration of a typical wellbore for heavy-oil application and listed the parameters responsible for the extent of heat loss. These included formation properties; cement sheath thermal conductivity; steam-injection rate; and steam quality. The paper also described the Zhang unified mechanistic model which involved the temperature, pressure, steam quality, and heat loss changes as a function of the depth and the surroundings. Recommendations for withstanding well operations, hole cleaning, and slurry placement were also presented. Insurance for incomplete drilling fluid displacement and cement with the ability to react and respond were also proposed. It was concluded that in thermal recovery wells, energy loss to the surroundings could be reduced by lowering the thermal conductivity of the cement sheath. This could greatly improve the economics of such wells. 9 refs., 5 figs.

Handgun waiting periods reduce gun deaths.

Science.gov (United States)

Luca, Michael; Malhotra, Deepak; Poliquin, Christopher

2017-11-14

Handgun waiting periods are laws that impose a delay between the initiation of a purchase and final acquisition of a firearm. We show that waiting periods, which create a "cooling off" period among buyers, significantly reduce the incidence of gun violence. We estimate the impact of waiting periods on gun deaths, exploiting all changes to state-level policies in the Unites States since 1970. We find that waiting periods reduce gun homicides by roughly 17%. We provide further support for the causal impact of waiting periods on homicides by exploiting a natural experiment resulting from a federal law in 1994 that imposed a temporary waiting period on a subset of states. Copyright © 2017 the Author(s). Published by PNAS.

Foamed Cement Interactions with CO₂

Energy Technology Data Exchange (ETDEWEB)

Verba, Circe [National Energy Technology Lab. (NETL), Albany, OR (United States); Montross, Scott [National Energy Technology Lab. (NETL), Albany, OR (United States). Oak Ridge Inst. for Science and Education (ORISE); Spaulding, Richard [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Dalton, Laura [National Energy Technology Lab. (NETL), Albany, OR (United States). Oak Ridge Inst. for Science and Education (ORISE); National Energy Technology Lab. (NETL), Morgantown, WV (United States); Crandall, Dustin [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Moore, Jonathan [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Glosser, Deborah [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Huerta, Nicolas [National Energy Technology Lab. (NETL), Albany, OR (United States); Kutchko, Barbara [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

2017-01-23

Geologic carbon storage (GCS) is a potentially viable strategy to reduce greenhouse emissions. Understanding the risks to engineered and geologic structures associated with GCS is an important first step towards developing practices for safe and effective storage. The widespread utilization of foamed cement in wells may mean that carbon dioxide (CO₂)/brine/foamed cement reactions may occur within these GCS sites. Characterizing the difference in alteration rates as well as the physical and mechanical impact of CO₂/brine/foamed cement is an important preliminary step to ensuring offshore and onshore GCS is a prudent anthropogenic CO₂ mitigation choice. In a typical oil and gas well, cement is placed in the annulus between the steel casing and formation rock for both zonal isolation and casing support. The cement must have sufficient strength to secure the casing in the hole and withstand the stress of drilling, perforating, and fracturing (e.g. API, 1997, 2010 Worldwide Cementing Practices). As such, measuring the mechanical and properties of cement is an important step in predicting cement behavior under applied downhole stresses (Nelson, 2006). Zonal isolation is the prevention of fluids migrating to different zones outside of the casing and is strongly impacted by the permeability of the wellbore cement (Nelson, 2006). Zonal isolation depends on both the mechanical behavior and permeability (a physical property) of the cement (Mueller and Eid, 2006; Nelson, 2006). Long-term integrity of cement depends on the mechanical properties of the cement sheath, such as Young’s Modulus (Griffith et al., 2004). The cement sheath’s ability to withstand the stresses from changes in pressure and temperature is predominantly determined by the mechanical properties, including Young’s modulus, Poisson’s ratio, and tensile strength. Any geochemical alteration may impact both the mechanical and physical properties of the cement, thus

Natural cement as the precursor of Portland cement: Methodology for its identification

International Nuclear Information System (INIS)

Varas, M.J.; Alvarez de Buergo, M.; Fort, R.

2005-01-01

When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed. The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements

Contoured-gap coaxial guns for imploding plasma liner experiments

Science.gov (United States)

Witherspoon, F. D.; Case, A.; Brockington, S.; Cassibry, J. T.; Hsu, S. C.

2014-10-01

Arrays of supersonic, high momentum flux plasma jets can be used as standoff compression drivers for generating spherically imploding plasma liners for driving magneto-inertial fusion, hence the name plasma-jet-driven MIF (PJMIF). HyperV developed linear plasma jets for the Plasma Liner Experiment (PLX) at LANL where two guns were successfully tested. Further development at HyperV resulted in achieving the PLX goal of 8000 μg at 50 km/s. Prior work on contoured-gap coaxial guns demonstrated an approach to control the blowby instability and achieved substantial performance improvements. For future plasma liner experiments we propose to use contoured-gap coaxial guns with small Minirailgun injectors. We will describe such a gun for a 60-gun plasma liner experiment. Discussion topics will include impurity control, plasma jet symmetry and topology (esp. related to uniformity and compactness), velocity capability, and techniques planned for achieving gun efficiency of >50% using tailored impedance matched pulse forming networks. Mach2 and UAH SPH code simulations will be included. Work supported by US DOE DE-FG02-05ER54810.

Unusual Case of Suicide With a Modified Trap Gun.

Science.gov (United States)

Vadysinghe, Amal; Dassanayake, Prasanna; Wickramasinghe, Medhani

2017-06-01

Trap gun is an illegal, locally manufactured gun with a basic trip system used to hunt wild animals. The body of a 28-year-old man was found in the jungle in supine position with both legs apart. A trap gun was between the legs pointing toward the cranial side of the body. It had 2 free wires that were not connected together. There was no evidence of foul play.The body had a single-entry wound (2.5-cm diameter) in the anterior chest, with blackening, burning, and tattooing. Six metal particles and nylon clothing material were embedded into soft tissue. No exit wound was found. Toxicology analysis reported an alcohol level of 72 mg/dL. The cause of death was multiple shrapnel injury to the chest at close to intermediate range by a single discharge from a trap gun. Circumstance was concluded as suicide.Ballistic and firearm experts opined that an illegal, manually operated, battery-powered ignition device was used to ignite the gun powder. We report the first case of suicide by a modified trap gun in literature.

Self-bunching electron guns

CERN Document Server

Mako, F; Weilhammer, Peter

1999-01-01

We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated cold emission, long life, and tolerance to contamination. The cold emission process is based on secondary electron emission. FMT has studied this resonant bunching process which gives rise to high current densities (0.01-5 kA/cm/sup 2/), high charge bunches (up to 100 nC/bunch), and short pulses (1-100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ~5% of the RF period. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ~40 ps long microbunches at ~20 A/cm/sup 2/ without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 mu s-long macro- pulses. About 5.8*10/sup 13/ micro-bunches or 62,000 coulombs have pass...

Beam emittance measurement from CERN thermionic guns

International Nuclear Information System (INIS)

Kester, O.; Rao, R.; Rinolfi, L.

1992-01-01

In the LEP Injector Linacs (LIL) a thermionic gun provides electron beams with different peak intensities at an energy of 80 keV. The beam emittances were estimated from the EGUN programme. Since the gun is of triode type, the main contribution to the emittance comes from the grid. The simulation programme does not model the real geometry by assuming a cylindrical symmetry, while the grid does not have such symmetry. A Gun Test Facility (GTF), allowing emittance measurements, based on the 3-gradients-method was installed. The experimental results are presented. (author) 6 refs.; 6 figs

Field reversal produced by a plasma gun

International Nuclear Information System (INIS)

Hartman, C.W.; Condit, W.; Granneman, E.H.A.; Prono, D.; Smith, A.C. Jr.; Taska, J.; Turner, W.C.

1980-01-01

Experimental results are presented of the production of Field-Reversed Plasma with a high energy coaxial plasma gun. The gun is magnetized with solenoids inside the center electrode and outside the outer electrode so that plasma emerging from the gun entrains the radial fringer field at the muzzle. The plasma flow extends field lines propagating a high electrical conductivity, the flux inside the center electrode should be preserved. However, for low flux, the trapped flux exceeds by 2 or more the initial flux, possibly because of helical deformation of the current channel extending from the center electrode

Alpha Fuels Environmental Test Facility impact gun

International Nuclear Information System (INIS)

Anderson, C.G.

1978-01-01

The Alpha Fuels Environmental Test Facility (AFETF) impact gun is a unique tool for impact testing 238 PuO 2 -fueled heat sources of up to 178-mm dia at velocities to 300 m/s. An environmentally-sealed vacuum chamber at the muzzle of the gun allows preheating of the projectile to 1,000 0 C. Immediately prior to impact, the heat source projectile is completely sealed in a vacuum-tight catching container to prevent escape of its radioactive contents should rupture occur. The impact velocity delivered by this gas-powered gun can be regulated to within +-2%

Design study on an independently-tunable-cells thermionic RF gun

International Nuclear Information System (INIS)

Hama, H.; Tanaka, T.; Hinode, F.; Kawai, M.

2006-01-01

Characteristics of a thermionic RF gun have been studied by a 3-D simulation code developed using an FDTD (Finite Difference Time Domain) method as a Maxwell's equations solver. The gun is consists of two independent power feeding cavities, so that we call it independently-tunable-cells (ITC)'-RF gun. The first cell is the cathode cell and the second one is an accelerating cell. The ITC gun can be operated at various modes of different RF-power ratio and phase between two cavities. Simulation study shows a velocity-bunching like effect may be occurred in the gun, so that the short pulse beam from the thermionic RF gun is a better candidate to produce the coherent THz synchrotron radiation. Expected bunch length with a total charge of ∼20 pC (1% energy width from the top energy) is around 200 fs (fwhm). Even the beam energy extracted from the gun is varied by which the input powers are changed, almost same shape of the longitudinal phase space can be produced by tuning the phase. (author)

Youth, Guns, and the Juvenile Justice System. Research Report.

Science.gov (United States)

Butts, Jeffrey; Coggeshall, Mark; Gouvis, Caterina; Mears, Daniel; Travis, Jeremy; Waul, Michelle; White, Ruth

This report documents trends in youth gun violence and the response within the justice system, noting the growing variety of data resources available to investigate the effect of new gun laws on youth, communities, and public safety. The first section reviews recent trends, examining the major wave of gun violence in the United States during the…

Guns, Suicide, COPD and Sleep

Directory of Open Access Journals (Sweden)

Robbins RA

2018-03-01

Full Text Available No abstract available. Article truncated at 150 words. Within the past year two tragic events, the shootings in Las Vegas and Florida have renewed the debate about guns. The politics and the money that fuels the political debate have sharply divided politicians. As tragic as these mass shootings are, deaths by suicide far outnumber the loss of live in these shootings. In 2014 suicide was the tenth most common cause of death with 42,826 lives lost (1. Half of the suicides were by firearm (21,386. The medical profession has traditionally been reluctant to speak about politically sensitive issues such as abortion, sexuality, and guns. However, beginning early in this millennium some medical societies such as the American Academy of Pediatrics, the US Preventative Services Task Force and even the Department of Veterans Affairs were suggesting physicians ask patients about gun behavior, but a few patients complained (2-5. There were some anecdotal reports of patients feeling “pressured” to answer …

Water guns affect abundance and behavior of bigheaded carp and native fish differently

Science.gov (United States)

Rivera, Jose; Glover, David C.; Kocovsky, Patrick; Garvey, James E.; Gaikowski, Mark; Jensen, Nathan R.; Adams, Ryan F.

2017-01-01

Water guns have shown the potential to repel nuisance aquatic organisms. This study examines the effects of exposure to a 1966.4 cm3 seismic water gun array (two guns) on the abundance and behavior of Bighead Carp Hypophthalmichthys nobilis, Silver Carp H. molitrix (collectively referred to as bigheaded carp) and native fishes (e.g., Smallmouth Buffalo Ictiobus bubalus). Water guns were deployed in a channel that connects the Illinois River to backwater quarry pits that contained a large transient population of bigheaded carp. To evaluate the effect of water guns, mobile side-looking split-beam hydroacoustic surveys were conducted before, during and between replicated water gun firing periods. Water guns did not affect abundance of bigheaded carp, but abundance of native fish detected during the firing treatment was 43 and 34% lower than the control and water guns off treatments, respectively. The proximity of bigheaded carp to the water gun array was similar between the water guns on and water guns off treatments. In contrast, the closest detected native fish were detected farther from the water guns during the water guns on treatment (mean ± SE, 32.38 ± 3.32 m) than during the water guns off treatment (15.04 ± 1.59 m). The water gun array had a greater impact on native fish species than on bigheaded carp. Caution should be taken to the extrapolation of these results to other fish species and to fish exposed to water guns in different environments (e.g., reduced shoreline interaction) or exposure to a larger array of water guns, or for use of water guns for purposes other than a barrier.

Water guns affect abundance and behavior of bigheaded carp and native fish differently

Science.gov (United States)

Rivera, Jose; Glover, David C.; Kocovsky, Patrick; Garvey, James E.; Gaikowski, Mark; Jensen, Nathan R.; Adams, Ryan F.

2018-01-01

Water guns have shown the potential to repel nuisance aquatic organisms. This study examines the effects of exposure to a 1966.4 cm3 seismic water gun array (two guns) on the abundance and behavior of Bighead Carp Hypophthalmichthys nobilis, Silver Carp H. molitrix (collectively referred to as bigheaded carp) and native fishes (e.g., Smallmouth Buffalo Ictiobus bubalus). Water guns were deployed in a channel that connects the Illinois River to backwater quarry pits that contained a large transient population of bigheaded carp. To evaluate the effect of water guns, mobile side-looking split-beam hydroacoustic surveys were conducted before, during and between replicated water gun firing periods. Water guns did not affect abundance of bigheaded carp, but abundance of native fish detected during the firing treatment was 43 and 34% lower than the control and water guns off treatments, respectively. The proximity of bigheaded carp to the water gun array was similar between the water guns on and water guns off treatments. In contrast, the closest detected native fish were detected farther from the water guns during the water guns on treatment (mean ± SE, 32.38 ± 3.32 m) than during the water guns off treatment (15.04 ± 1.59 m). The water gun array had a greater impact on native fish species than on bigheaded carp. Caution should be taken to the extrapolation of these results to other fish species and to fish exposed to water guns in different environments (e.g., reduced shoreline interaction) or exposure to a larger array of water guns, or for use of water guns for purposes other than a barrier.

Gun utopias? Firearm access and ownership in Israel and Switzerland

OpenAIRE

Rosenbaum, Janet

2011-01-01

The 2011 attempted assassination of a US representative renewed the national gun control debate. Gun advocates claim that mass-casualty events are mitigated and deterred with three policies: (1) permissive gun laws, (2) widespread gun ownership, (3) encouragement of armed civilians who can intercept shooters, and cite Switzerland and Israel as exemplars. We evaluate these claims with analysis of International Crime Victimization Survey (ICVS) data and translation of laws and original source m...

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: HVLP COATING EQUIPMENT, ITW AUTOMOTIVE REFINISHING, DEVILBISS FLG-631-318 HVLP SPRAY GUN

Science.gov (United States)

This report presents the results of the verification test of the DeVilbiss FLG-631-318 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the DeVilbiss FLG, which is designed for use in automotive refinishing. The test coating chosen by ITW Automotive Refi...

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: HVLP COATING EQUIPMENT, ITW AUTOMOTIVE REFINISHING, DEVILBISS GTI-600G, HVLP SPRAY GUN

Science.gov (United States)

This report presents the results of the verification test of the DeVilbiss GTi-600G high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the DeVilbiss GTi, which is designed for use in automotive refinishing. The test coating chosen by ITW Automotive Refinis...

Diagnostic Suite for HyperV Coaxial Plasma Gun Development for the PLX- α Project

Science.gov (United States)

Case, Andrew; Brockington, Sam; Witherspoon, F. Douglas

2015-11-01

We present the diagnostic suite to be used during development of the coaxial guns HyperV will deliver to LANL in support of the ARPA-E Accelerating Low-Cost Plasma Heating And Assembly (ALPHA) program. For plasma jet diagnostics this includes fast photodiodes for velocimetry, a ballistic pendulum for measuring total plasmoid momentum, interferometry for line integrated plasma density, deflectometry for line integrated perpendicular density gradient measurements, and spectroscopy, both time resolved high resolution spectroscopy using a novel detector developed by HyperV and time integrated survey spectroscopy, for measurements of velocity and temperature as well as impurities. In addition, we plan to use fast pressure probes for stagnation pressure, a Faraday cup for density, fast imaging for plume geometry and time integrated imaging for overall light emission. A novel low resolution long record length camera developed by HyperV will also be used for plume diagnostics. For diagnostics of gun operation, we will use Rogowski coils to measure current, voltage dividers for voltages, B-dot probes for magnetic field, and time resolved fast photodiodes to measure plasmoid velocity inside the accelerator. This work supported by the ARPA-E ALPHA program.

Feasibility of producing nano cement in a traditional cement factory in Iraq

Directory of Open Access Journals (Sweden)

Sada Abdalkhaliq Hasan Alyasri

2017-12-01

Full Text Available This study investigates the economic feasibility of producing nano cement through the establishment of a production line within an existing cement factory. Creating a nano cement production line within the Alkufa Cement factory in Iraq is selected as a case study. Evaluation measures including internal rate of return (IRR, net present value (NPV and breakeven point (BEP are used to evaluate the possible gain that can be achieved from this option. The results demonstrated a positive NPV. The IRR is found to be 26.8% and BEP is reached within 3 years after the establishment of the line. This indicates that producing nano cement in the existing cement factory is economically feasible and can be more advantageous than the ordinary cement.

The mechanical effect of the existing cement mantle on the in-cement femoral revision.

Science.gov (United States)

Keeling, Parnell; Lennon, Alexander B; Kenny, Patrick J; O'Reilly, Peter; Prendergast, Patrick J

2012-08-01

Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct. Primary cement mantles were formed by cementing a polished stem into sections of tubular steel. If in the test group, the mantle underwent conditioning in saline to simulate ageing and was subject to a fatigue of 1 million cycles. If in the control group no such conditioning or fatigue was carried out. The cement-in-cement procedure was then undertaken. Both groups underwent a fatigue of 1 million cycles subsequent to the revision procedure. Application of a Mann-Whitney test on the recorded subsidence (means: 0.51, 0.46, n=10+10, P=0.496) and inducible displacement (means: 0.38, 0.36, P=0.96) revealed that there was no statistical difference between the groups. This study represents further biomechanical investigation of the mechanical behaviour of cement-in-cement revision constructs. Results suggest that pre-revision fatigue and ageing of the cement may not be deleterious to the mechanical performance of the revision construct. Thus, this study provides biomechanical evidence to back-up recent successes with this useful revision technique. Copyright © 2012 Elsevier Ltd. All rights reserved.

Gun Trafficking and the Southwest Border

Science.gov (United States)

2009-07-29

felons, drug traffickers, and juvenile gang members from acquiring firearms from gun traffickers. These criminals often acquire firearms from persons...renounced their U.S. citizenship; (8) persons restrained under a court-order from harassing, stalking , or threatening an intimate partner or child of... gang members from acquiring firearms from gun traffickers. These criminals often acquire firearms from a person who otherwise is not prohibited to

Improved DC Gun and Insulator Assembly

Energy Technology Data Exchange (ETDEWEB)

Neubauer, Michael [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2015-01-11

Many user facilities such as synchrotron radiation light sources and free electron lasers rely on DC high voltage photoguns with internal field gradients as high as 10 to 15 MV/m. These high gradients often lead to field emission which poses serious problems for the photocathode used to generate the electron beam and the ceramic insulators used to bias the photocathode at high voltage. Ceramic insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons bury themselves in the ceramic causing a buildup of charge and eventual puncture, and also because large diameter ceramics are difficult to braze reliably. The lifetimes of photo cathodes inside high current DC guns exhibiting field emission are limited to less than a hundred hours. Reducing the surface gradients on the metals reduces the field emission, which serves to maintain the required ultrahigh vacuum condition. A novel gun design with gradients around 5 MV/m and operating at 350 kV, a major improvement over existing designs, was proposed that allows for the in-situ replacement of photo cathodes in axially symmetric designs using inverted ceramics. In this project, the existing JLAB CEBAF asymmetric gun design with an inverted ceramic support was modeled and the beam dynamics characterized. An improved structure was designed that reduces the surface gradients and improves the beam optics. To minimize the surface gradients, a number of electrostatic gun designs were studied to determine the optimum configuration of the critical electrodes within the gun structure. Coating experiments were carried out to create a charge dissipative coating for cylindrical ceramics. The phase II proposal, which was not granted, included the design and fabrication of an axially symmetric DC Gun with an inverted ceramic that would operate with less than 5 MV/m at 350 kV and would be designed with an in-situ replaceable photo-cathode.

ELECTRON GUN

Science.gov (United States)

Christofilos, N.C.; Ehlers, K.W.

1960-04-01

A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

Where have all the gun deaths gone?

African Journals Online (AJOL)

Gun violence denialists recently dismissed the findings of two studies presented at a seminar co-hosted by Gun Free South Africa, the. Institute for Security Studies and the African. Policing Civilian Oversight Forum. Abrahams et al.[1] compared the profile of female homicides from two representative national samples.

Gun Control: The Debate and Public Policy.

Science.gov (United States)

Watkins, Christine

1997-01-01

Provides an overview and background information on the debate over gun control, as well as several teaching ideas. Handouts include a list of related topics drawn from various disciplines (economics, U.S. history), seven arguments for and against gun control, and a set of policy evaluation guidelines. (MJP)

Evaluation of high frequency ghost cavitation emissions for two different seismic air-gun arrays using numerical modelling

Science.gov (United States)

Khodabandeloo, Babak; Landrø, Martin

2017-04-01

Sound is deployed by marine mammals for variety of vital purposes such as finding food, communication, echolocation, etc. On the other hand human activities generate underwater noise. One major type of acoustic source is marine seismic acquisition which is carried out to image layers beneath the seabed exploiting reflected acoustic and elastic waves. Air-gun arrays are the most common and efficient marine seismic sources. Field measurements using broad band hydrophones have revealed that acoustic energies emitted by air-gun arrays contains frequencies from a few Hz up to tens of kHz. Frequencies below 200 Hz benefit seismic imaging and the rest is normally considered as wasted energy. On the other hand, the high frequency range (above 200 Hz) overlaps with hearing curves of many marine mammals and especially toothed whales and may have an impact on their behavior. A phenomenon called ghost cavitation is recently recognized to be responsible for a major part of these high frequencies (> 5 kHz). Acoustic pressure waves of individual air guns reflected from sea surface can cause the hydrostatic pressure to drop towards zero close to the source array. In these regions there is a high probability for water vapor cavity growth and subsequent collapse. We have simulated ghost cavitation cloud using numerical modelling and the results are validated by comparing with field measurements. The model is used to compare the amount of high frequency noise due to ghost cavitation for two different air gun arrays. Both of the arrays have three subarrays but the array distance for the one with 2730 in3 air volume is 6 meters and for the slightly bigger array (3250 in3 in air volume) the subarrays are separated by 8 meters. Simulation results indicate that the second array, despite larger subarray distance, generates stronger ghost cavitation signal.

Sustainable Development of the Cement Industry and Blended Cements to Meet Ecological Challenges

Directory of Open Access Journals (Sweden)

Konstantin Sobolev

2003-01-01

Full Text Available The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and - at the same time - uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

Cement for Oil Well Cementing Operations in Ghana

African Journals Online (AJOL)

Michael

For Portland cement to qualify as oil well cement, the chemical and physical properties must meet ..... Reservoir Engineering, Stanford University,. Stanford, California, pp. ... Construction”, PhD Thesis, Kwame Nkrumah. University of Science ...

Assessment of geotechnical properties of uncemented/cemented clayey soil incorporated with waste crumb rubber

Directory of Open Access Journals (Sweden)

JITENDRA SINGH YADAV

2017-03-01

Full Text Available Discarded waste tires are becoming a serious threat to health, environment, and ecological systems worldwide if it is not disposed of properly. Every year 1000 million of waste tires are discarded. This number may grow up to 1200 million by the year 2030. On the other hand, construction of civil engineering structures such as buildings, dams, highways, etc. are at high risk of differential settlement, especially in the case of weak or soft clay, which is due to its low shear strength and high compressibility. The paper aims to assess geotechnical properties of uncemented/cemented clayey soil incorporated with waste crumb rubber. Compaction parameters, unconfined compressive strength, split tensile strength, toughness index, CBR values and swelling pressure of rubberized uncemented/cemented clayey soil (3%, and 6% cement and different percentage of crumb rubber have been obtained. After rigorous extensive study, it has been concluded that unconfined compressive strength and split tensile strength of rubberized cemented clayey soil decreases with the increase of the percentage of crumb rubber whereas the axial, and diametral strain are found to be increased with the addition of crumb rubber up to 5% after that it starts to decrease. The CBR values, swelling pressure, and toughness index of uncemented/cemented clayey soil was significantly affected by incorporation of crumb rubber. SEM studies have also been incorporated in this investigation.

Performance of the Brookhaven photocathode rf gun

International Nuclear Information System (INIS)

Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fischer, J.; Fisher, A.S.; Gallardo, J.; Ingold, G.; Kirk, H.G.; Leung, K.P.; Malone, R.; Pogorelsky, I.; Srinivasan-Rao, T.; Rogers, J.; Tsang, T.; Sheehan, J.; Ulc, S.; Woodle, M.; Xie, J.; Zhang, R.S.; Lin, L.Y.; McDonald, K.T.; Russell, D.P.; Hung, C.M.; Wang, X.J.

1991-01-01

The Brookhaven Accelerator Test Facility (ATF) uses a photocathode rf gun to provide a high-brightness electron beam intended for FEL and laser-acceleration experiments. The rf gun consists of 1 1/2 cells driven at 2856 MHz in π-mode with a maximum cathode field of 100 MV/m. To achieve long lifetimes, the photocathode development concentrates on robust metals such as copper, yttrium and samarium. We illuminate these cathodes with a 10-ps, frequency-quadrupled Nd:YAG laser. We describe the initial operation of the gun, including measurements of transverse and longitudinal emittance, quantum efficiencies, and peak current. The results are compared to models

Emittance compensation of CW DC-gun photoinjector

International Nuclear Information System (INIS)

Li Peng; Wu Dai; Xu Zhou; Li Ming; Yang Xingfan

2011-01-01

Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)

Low force cementation.

Science.gov (United States)

Wilson, P R

1996-07-01

The marginal adaptation of full coverage restorations is adversely affected by the introduction of luting agents of various minimum film thicknesses during the cementation process. The increase in the marginal opening may have long-term detrimental effects on the health of both pulpal and periodontal tissues. The purpose of this study was to determine the effects of varying seating forces (2.5, 12.5, 25 N), venting, and cement types on post-cementation marginal elevation in cast crowns. A standardized cement space of 40 microns was provided between a machined gold crown and a stainless steel die. An occlusal vent was placed that could be opened or closed. The post-cementation crown elevation was measured, following the use of two commercially available capsulated dental cements (Phosphacap, and Ketac-cem Applicap). The results indicate that only the combination of Ketac-Cem Applicap and crown venting produced post-cementation crown elevation of less than 20 microns when 12.5 N seating force was used. Higher forces (25 N) and venting were required for comparable seating when using Phosphacap (19 microns). The amount of force required to allow maximum seating of cast crowns appears to be cement specific, and is reduced by effective venting procedures.

Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance

Science.gov (United States)

Chen, Irvin Allen

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate

Low Energy Electron Gun on Board a Scientific Satellite GEOTAIL

OpenAIRE

TSUTSUI, Minoru; ONISHI, Yoshiaki; MATSUMOTO, Hiroshi; KIMURA, Iwane; 筒井, 稔; 大西, 嘉昭; 松本, 紘; 木村, 磐根

1988-01-01

A low energy electron gun to be used for beam-plasma interaction experiments by a scientific satellite GEOTAIL has been designed and manufactured. Electrodes of the gun have been modified from the Pierce type gun because of the use of a directly heated cathode. Spatial density distributions of beam electrons emitted from the new gun have been measured in a large vacuum chamber, and characteristic curves of emission currents for some beam energies and cathode powers have been checked repeatedl...

Development of beam diagnostic devices for characterizing electron guns

International Nuclear Information System (INIS)

Bhattacharjee, D.; Tiwari, R.; Jayaprakash, D.; Mishra, R.L.; Sarukte, H.; Waghmare, A.; Thakur, N.; Dixit, K.P.

2015-01-01

The electron guns for the DC accelerators and RF Linacs are designed and developed at EBC/APPD/BARC, Kharghar. These electron guns need to be characterized for its design and performance. Two test benches were developed for characterizing the electron guns. Various beam diagnostic devices for measuring beam currents and beam sizes were developed. Conical faraday cup, segmented faraday cup, slit scanning bellows movement arrangement, multi-plate beam size measurement setup, multi- wire beam size measurement setup, Aluminum foil puncture assembly etc. were developed and used. The paper presents the in-house development of various beam diagnostics for characterizing electron guns and their use. (author)

Ultrafine portland cement performance

Directory of Open Access Journals (Sweden)

C. Argiz

2018-04-01

Full Text Available By mixing several binder materials and additions with different degrees of fineness, the packing density of the final product may be improved. In this work, ultrafine cement and silica fume mixes were studied to optimize the properties of cement-based materials. This research was performed in mortars made of two types of cement (ultrafine Portland cement and common Portland cement and two types of silica fume with different particle-size distributions. Two Portland cement replacement ratios of 4% and 10% of silica fume were selected and added by means of a mechanical blending method. The results revealed that the effect of the finer silica fume mixed with the coarse cement enhances the mechanical properties and pore structure refinement at a later age. This improvement is somewhat lower in the case of ultrafine cement with silica fume.

Prospects for deflagration guns

International Nuclear Information System (INIS)

Cheng, D.Y.; Tripathi, P.P.; Chang, C.N.

1978-01-01

Deflagration is a process of fluid expansion with energy addition. Its existence in plasma physics was first discovered in the back-strapped T-tube experiments. In the coaxial plasma gun configuration the operation can be simple and yet produce a clean, high density (5 x 10 15 cm -3 ), and high kinetic energy (10 to 50 keV) collimated plasma beam. Plasma acceleration mechanism was thought to be driven by J x B force. Tapered electrodes have been used to obtain plasma beams. Scaling of the gun can be performed according to simple theory based on momentum and energy balance. Proposed plasma fueling and injection to magnetic fusion systems will be discussed

Differences Between New and Long-Standing US Gun Owners: Results From a National Survey.

Science.gov (United States)

Wertz, Joseph; Azrael, Deborah; Hemenway, David; Sorenson, Susan; Miller, Matthew

2018-07-01

To quantify the proportion of current US gun owners who are new to owning firearms and compare new versus long-standing gun owners with respect to their firearms and firearm-related behaviors. We performed a cross-sectional analysis of a nationally representative probability-based online survey conducted in 2015 in the United States. We defined new gun owners as current firearm owners who acquired all of their firearms within the past 5 years, but who lived in a home without a gun at some time over the past 5 years. We defined long-standing firearm owners as all other current gun owners. New gun owners represented 10% of all current US adult gun owners. In addition to being younger than long-standing gun owners, new gun owners were more likely to be liberal, own fewer guns, own handguns, own guns only for protection, and store guns in a safe manner. Gun ownership is dynamic, with approximately 1 million Americans becoming new gun owners each year. Public Health Implications. Clinical guidelines should be updated to explicitly endorse re-evaluating household firearm status at regular intervals.

Gun policy and serious mental illness: priorities for future research and policy.

Science.gov (United States)

McGinty, Emma Elizabeth; Webster, Daniel W; Barry, Colleen L

2014-01-01

In response to recent mass shootings, policy makers have proposed multiple policies to prevent persons with serious mental illness from having guns. The political debate about these proposals is often uninformed by research. To address this gap, this review article summarizes the research related to gun restriction policies that focus on serious mental illness. Gun restriction policies were identified by researching the THOMAS legislative database, state legislative databases, prior review articles, and the news media. PubMed, PsycINFO, and Web of Science databases were searched for publications between 1970 and 2013 that addressed the relationship between serious mental illness and violence, the effectiveness of gun policies focused on serious mental illness, the potential for such policies to exacerbate negative public attitudes, and the potential for gun restriction policies to deter mental health treatment seeking. Limited research suggests that federal law restricting gun possession by persons with serious mental illness may prevent gun violence from this population. Promotion of policies to prevent persons with serious mental illness from having guns does not seem to exacerbate negative public attitudes toward this group. Little is known about how restricting gun possession among persons with serious mental illness affects suicide risk or mental health treatment seeking. Future studies should examine how gun restriction policies for serious mental illness affect suicide, how such policies are implemented by states, how persons with serious mental illness perceive policies that restrict their possession of guns, and how gun restriction policies influence mental health treatment seeking among persons with serious mental illness.

Research of fluidized bed cement clinker sintering system by pilot plant; Ryudosho cement shosei gijutsu no kaihatsu. 7

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, T [Center for Coal Utilization, Japan, Tokyo (Japan); Sato, N; Hashimoto, I; Nakatsuka, M [The Cement Association of Japan, Tokyo (Japan)

1996-09-01

While a cement manufacturing process generally performs sintering by using a rotary kiln, a development work has been carried out as a subsidy operation of the Agency of Natural Resources and Energy on a cement sintering technology using a fluidized bed consisted of two furnaces: a jet flow bed granulating furnace and a fluidized bed sintering furnace. This paper reports the results of tests and researches performed during fiscal 1995. A plant with a scale of 20 ton-a-day production started in 1993 after having gone through bench scale tests. The year 1995 conducted by August its performance evaluation, review of the operation method and the safety criteria, and generalization of the tests. A multi-stage cyclone system has been employed in the preheating equipment for cement material powder. A number of improvements have been realized in the aspects of construction and operation, such as stabilization of dust collecting efficiency by employing a high-efficiency type cyclone, and operation with reduced pressure variation. Based on these results, a construction had been progressed in parallel on a new plant upscaled to 200 ton-a-day production. The new plant was completed in December, 1995. 9 figs., 8 tabs.

Radioactive waste cementation

International Nuclear Information System (INIS)

Soriano B, A.

1996-01-01

This research was carried out to develop the most adequate technique to immobilize low and medium-activity radioactive waste. different brands of national cement were used, portland and pozzolanic cement. Prismatic and cylindrical test tubes were prepared with different water/cement (W/C) relationship. Additives such a as clay and bentonite were added in some other cases. Later, the properties of these test tubes were evaluated. Properties such as: mechanical resistance, immersion resistance, lixiviation and porosity resistance. Cement with the highest mechanical resistance values, 62,29 MPa was pozzolanic cement for a W/C relationship of 0,35. It must be mentioned that the other types of cements reached a mechanical resistance over 10 MPa, a value indicated by the international standards for transportation and storage of low and medium-activity radioactive waste at a superficial level. However, in the case of immersion resistance, Sol cement (portland type I) with a W/C relationship of 0,35 reached a compression resistance over 61,92 MPa; as in the previous cases, the other cements reached a mechanical resistance > 10 MPa. Regarding porosity, working with W/C relationships = 0,35 0,40 and 0,45, without additives and with additives, the percentage of porosity found for all cements is lower than 40% percentage indicated by international standards. With regard to the lixiviation test, pozzolanic cement best retained Cesium-137 and Cobalt-60, and increased its advantages when bentonite was added, obtaining a lixiviation rate of 2,02 x E-6 cm/day. Sol cement also improved its properties when bentonite was added and obtained a lixiviation rate of 2,84 x E-6 cm/day for Cesium-137. However, Cobalt-60 is almost completely retained with the 3 types of cement with or without additives, reaching the limits indicated by the international standards for the lixiviation rate of beta-gamma emitter < 5,00E-4 cm/day. Characterizing the final product involves the knowledge of its

Characterization of the C-2W Plasma Guns

Science.gov (United States)

Dubois, Ami; Sokolov, Vladimir; Korepanov, Sergey; Osin, Dima; Player, Gabriel; TAE Team

2017-10-01

Previous use of coaxial arc discharge plasma guns on the C-2U device exhibited great success in plasma stabilization and improved confinement. On the C-2W experiment, arc discharge plasma guns will again be used to facilitate the electrical connection between the plasma core and the divertor electrodes in order to maintain the electrode edge biasing and induce E x B shear to control plasma rotation. Each plasma gun contains an internal solenoid used to shape the plasma stream. Characterization of electron density (ne) , electron temperature (Te) , floating potential (Vf) , and total plasma flux in an arc discharge lasting 6 ms without the internal solenoid are presented. A Langmuir probe located 27 cm axially outside of the plasma gun anode measures a bell-like radial ne profile with peak ne 1018 m-3 and Te 2 - 10 eV. Observed spectral lines of impurity ions provide an estimate of Te, and Balmer series line ratios of the main ion component are used to evaluate ne at both the probe location and near the plasma gun anode. A calorimeter measures the plasma flux to be constant and equivalent to 1 kA.

Parameters of Alumina Cement and Portland Cement with Addition of Chalcedonite Meal

Science.gov (United States)

Kotwa, Anna

2017-10-01

Aluminous cement is a quick binder with special properties. It is used primarily to make non-standard monolithic components exposed to high temperatures, + 1300°C. It is also a component of adhesives and mortars. It has a very short setting time. It is characterized by rapid increase in mechanical strength and resistance to aggressive sulphates. It can be used in reinforced concrete structures. Laying of concrete, construction mortar made of alumina cement can be carried out even at temperatures of -10°C. This article discusses a comparison of the parameters of hardened mortar made of alumina cement GÓRKAL 40 and Portland cement CEM I 42.5R. The mortars contain an addition of chalcedonite meal with pozzolanic properties, with particle size of less than 0.063μm. The meal was added in amounts of 5% and 20% of cement weight. Chalcedonite meal used in the laboratory research is waste material, resulting from chalcedonite aggregate mining. It has the same properties as the rock from which it originates. We have compared the parameters of hardened mortar i.e. compressive strength, water absorption and capillarity. The addition of 20% chalcedonite meal to mortars made from aluminous cement will decrease durability by 6.1% relative to aluminous cement mortar without addition of meal. Considering the results obtained during the absorbency tests, it can be stated that the addition of chalcedonite meal reduces weight gains in mortars made with cement CEM I 42.5 R and alumina cement. Use of alumina cement without addition of meal in mortars causes an increase of mass by 248% compared to Portland cement mortars without additions, in the absorption tests. The addition of chalcedonite meal did not cause increased weight gain in the capillary action tests. For the alumina cement mortars, a lesser weight gains of 24.7% was reported, compared to the Portland cement mortar after 28 days of maturing.

A new smart traffic monitoring method using embedded cement-based piezoelectric sensors

International Nuclear Information System (INIS)

Zhang, Jinrui; Lu, Youyuan; Lu, Zeyu; Liu, Chao; Sun, Guoxing; Li, Zongjin

2015-01-01

Cement-based piezoelectric composites are employed as the sensing elements of a new smart traffic monitoring system. The piezoelectricity of the cement-based piezoelectric sensors enables powerful and accurate real-time detection of the pressure induced by the traffic flow. To describe the mechanical-electrical conversion mechanism between traffic flow and the electrical output of the embedded piezoelectric sensors, a mathematical model is established based on Duhamel’s integral, the constitutive law and the charge-leakage characteristics of the piezoelectric composite. Laboratory tests show that the voltage magnitude of the sensor is linearly proportional to the applied pressure, which ensures the reliability of the cement-based piezoelectric sensors for traffic monitoring. A series of on-site road tests by a 10 tonne truck and a 6.8 tonne van show that vehicle weight-in-motion can be predicted based on the mechanical-electrical model by taking into account the vehicle speed and the charge-leakage property of the piezoelectric sensor. In the speed range from 20 km h −1 to 70 km h −1 , the error of the repeated weigh-in-motion measurements of the 6.8 tonne van is less than 1 tonne. The results indicate that the embedded cement-based piezoelectric sensors and associated measurement setup have good capability of smart traffic monitoring, such as traffic flow detection, vehicle speed detection and weigh-in-motion measurement. (paper)

Guns and Fear: A One-Way Street?

Science.gov (United States)

Hauser, Will; Kleck, Gary

2013-01-01

Surveys show that more than one half of gun owners report owning their firearm for self-protection. Although research has examined the effect of fear of crime on gun ownership, the issue of reciprocity and temporal order has been largely ignored. Furthermore, the effect of firearm acquisition and relinquishment on fear has not been evaluated…

Gun Violence and Children: Factors Related To Exposure and Trauma.

Science.gov (United States)

Slovak, Karen

2002-01-01

Study investigated relationship between access to firearms and parental monitoring on rural youths' exposure to gun violence, and examined the effect of gun violence exposure on mental health. Results indicated a substantial number were exposed to gun violence. Exposure was related to firearm access and parental monitoring. Implications for social…

Analysis on a electron gun for metal fusion

International Nuclear Information System (INIS)

Paes, A.C.J.; Galvao, R.M.O.; Boscolo, P.; Passaro, A.

1987-09-01

The characteristics of the electron beam of the HK-011600 Δ, electron gun for metal fusion at the 'Divisao de Materiais do Instituto de Pesquisa e Desenvolvimento do CTA (PMR/IPD/CTA)', is analyzed. In this analysis, the Pierce gun model and the SLAC computational code for electron optics are used. The electron beam R and Z profiles are obtained in the gun region and in the magnetic lenses region. The behaviour of the electron beam in the prism region is also discussed using a simple model. (author) [pt

Method of electron emission control in RF guns

International Nuclear Information System (INIS)

Khodak, I.V.; Kushnir, V.A.

2001-01-01

The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described

Method of electron emission control in RF guns

CERN Document Server

Khodak, I V

2001-01-01

The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described.

Non-channel magnetron gun as the electron source for resonance linear accelerator

International Nuclear Information System (INIS)

Ivanov, G.M.; Makhnenko, L.A.; Cherenshchikov, S.A.

1999-01-01

Studies on the magnetron gun with a cold cathode being part of linear accelerator on the travelling wave are described. Two modes of the gun operation differing by presence of UHF field of the pre-buncher near the gun are observed. In the mode without UHF field the short (about 2 ns) pulses of accelerated electrons with amplitude up to 0.5 A at the gun current up to 20 A were obtained. The presence of UHF field near the gun makes it possible to obtain the beam of higher duration (up to 1.0 μs), but with current up to 20 mA at the accelerator outlet and up to 1 A at the gun outlet. The mechanism of the gun operation is concerned with the secondary-electron current increase and setting self-sustaining secondary emission. Gun characteristics under study are acceptable for the purposes of injection into accelerator [ru

Performance of photocathode rf gun electron accelerators

International Nuclear Information System (INIS)

Ben-Zvi, I.

1993-01-01

In Photo-Injectors (PI) electron guns, electrons are emitted from a photocathode by a short laser pulse and then accelerated by intense rf fields in a resonant cavity. The best known advantage of this technique is the high peak current with a good emittance (high brightness). This is important for short wavelength Free-Electron Lasers and linear colliders. PIs are in operation in many electron accelerator facilities and a large number of new guns are under construction. Some applications have emerged, providing, for example, very high pulse charges. PIs have been operated over a wide range of frequencies, from 144 to 3000 MHz (a 17 GHz gun is being developed). An exciting new possibility is the development of superconducting PIs. A significant body of experimental and theoretical work exists by now, indicating the criticality of the accelerator elements that follow the gun for the preservation of the PI's performance as well as possible avenues of improvements in brightness. Considerable research is being done on the laser and photocathode material of the PI, and improvement is expected in this area

Modifications Of A Commercial Spray Gun

Science.gov (United States)

Allen, Peter B.

1993-01-01

Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

Photocathode operation of a thermionic RF gun

International Nuclear Information System (INIS)

Thorin, S.; Cutic, N.; Lindau, F.; Werin, S.; Curbis, F.

2009-01-01

The thermionic RF gun using a BaO cathode at the MAX-lab linac injector has been successfully commissioned for additional operation as a photocathode gun. By retaining the BaO cathode, lowering the temperature below thermal emission and illuminating it with a UV (263 nm) 9 ps laser pulse a reduced emittance and enhanced emission control has been achieved. Measurements show a normalised emittance of 5.5 mm mrad at 200 pC charge and a maximum quantum efficiency of 1.1x10 -4 . The gun is now routinely switched between storage ring injections in thermionic mode and providing a beam for the MAX-lab test FEL in photocathode mode.

Technological guns which form the profiled electron beans

International Nuclear Information System (INIS)

Mel'nik, V.I.

1998-01-01

Electron guns with high-voltage glow discharge are developed which form disc - and tubule-like,hollow conic and linear electron beams,as well as devices and systems for control of gun parameter and technological processes in low and intermediate vacuum

The breakdown phase in a coaxial plasma gun

International Nuclear Information System (INIS)

Donges, A.; Herziger, G.; Krompholz, H.; Ruehl, F.; Schoenbach, K.

1980-01-01

The electrical breakdown in a coaxial plasma gun was investigated by means of optical and electrical measurements. The optimum start and operation conditions of the gun turned out to be strongly dependent on material and length of the cylindrical insulator. (orig.)

Investigation of pellet acceleration by an arc heated gas gun

International Nuclear Information System (INIS)

Andersen, P.; Andersen, S.A.; Bundgaard, J.; Baekmark, L.; Hansen, B.H.; Jensen, V.O.; Kossek, H.; Michelsen, P.K.; Nordskov, A.; Sass, B.; Soerensen, H.; Weisberg, K.V.

1987-06-01

This report describes work on pellet acceleration by means of an arc heated gas gun. The work is a continuation of the work described in RISO-M-2536. The aim of the work is to obtain velocities well above 2 km/s for 3.2 mm diameter deuterium pellets. By means of a cryogenic arc chamber in which the hydrogen propellant is pre-condensed, extruded deutetrium pellets are accelerated up to a maximum velocity of 1.93 km/s. When increasing the energy input to the arc in order to increase the pellet velocity further the heat input to the extrusion/punching pellet loading mechanism was found to be critical: preparation of pellets became difficult and cooling times between shots became inconveniently long. In order to circumvent this problems the concept of a room temperature hydrogen propellant pellet fed arc chamber was proposed. Preliminary results from acceleration of polyurethane pellets with this arc chamber are described as well as the work of developing of feed pellet guns for this chamber. Finally the report describes design consideration for a high pressure propellant pellet fed arc chamber together with preliminary results obtained with a proto-type arc chamber. (author)