Range Of Energy Inputs Research Articles

Interfragmentary surface area as an index of comminution energy: proof of concept in a bone fracture surrogate

Fracture mechanics theory postulates a monotonic relationship between energy absorption and fracture surface generation. We hypothesized that this relationship was demonstrable to the point that, on a continuous scale, comminuted fractures created with disparate levels of energy delivery could be discriminated. Using a bone fracture surrogate in conjunction with digital image analysis of CT fracture data, we measured the surface area freed by controlled, discrete fracture simulations. Prior to these simulations, the reproducibility of the digital image analysis algorithm was validated with repeated measurements by two different operators. The parametric fracture series results showed a statistically significant difference in measured de novo surface area between four specimen groups, over a range of input energies from 1.4×10 10–9.1×10 10 J/m 3 (or 12.5–80.2 J/specimen). The results of this study provide confirmation that comminution severity can indeed be measured on a continuous scale, based on energy absorption (another clinically meaningful index).

A 100 mJ Table-Top Short Pulse Amplifier for 248 nm Using Interferometric Multiplexing

A polarization multiplexing method (based on Sagnac interferometer’s principle) was used in combination with a table-top wide aperture discharge pumped excimer amplifier to amplify femtosecond UV pulses. It is possible to optimize the operational conditions of the device within a wide range of input energies by changing the optical setup, while keeping the signal-to-noise ratio (short pulse – amplified spontaneous emission (ASE) ratio) of the pulses on a reasonably low value. The amplifier was tested for two different front ends. With ∼40 μJ input energy ∼50 mJ output energy was obtained in a 3-pass arrangement, and applying a seed pulse carrying an energy of around 2–3 mJ a maximum output energy of 100 mJ was reached in a single subpicosecond beam at 248 nm.

Coupling of methane under pulse corona plasma (I)

At normal temperature and pressure, pulse corona plasma was used as a new method for the dehydrogenative coupling of methane in the absence of oxygen. The effects of voltage polarity and input energy on the dehydrogenative coupling of methane were investigated. The parameter “energy efficiency” was introduced to examine the coupling of the input energy and the dehydrogenative coupling of methane. The experimental results show that positive corona gives higher energy efficiency than negative corona. When the positive corona was chosen, C2 yield per pass was 31.6% and acetylene yield per pass was 30.1% with 44.6% methane conversion at an input energy density of 1788kJ/mol and a pulse repetition frequency of 66Hz. The function of input energy density towards methane conversion may be expressed as a formula of-In(1-X) =k (PIF). In the range of input energy employed, C2 yield is proportional to input energy density, but energy efficiency drops off with increasing input energy density.

Two-channel analysis of QUELL experimental results

We have improved the model presently used in the thermo-hydraulic code Gandalf, adapting it to cable-in-conduit conductors with central cooling channel such as those developed for the model coils of ITER. In particular the helium flow in an arbitrary number of parallel channels have now independent velocity and thermodynamic state (pressure and temperature). We demonstrate the capability of the new model by means of comparison to measurements taken during the QUELL experiment in SULTAN. We compare in particular data on heat slug at zero current and field in a broad range of energy inputs, as well as data on quench propagation, to simulation results obtained with the single channel approximation and the newly implemented two-channel model. The latter achieves significantly better agreement with experimental data, in particular in the case of slow heating transients such as in heat slug propagation tests.

Coupling of methane under pulse corona plasma (I)— — In the absence of oxygen

At normal temperature and pressure, pulse corona plasma was used as a new method for the dehydrogenative coupling of methane in the absence of oxygen. The effects of voltage polarity and input energy on the dehydrogenative coupling of methane were investigated. The parameter "energy efficiency" was introduced to examine the coupling of the input energy and the dehydrogenative coupling of methane. The experimental results show that positive corona gives higher energy efficiency than negative corona. When the positive corona was chosen, C-2 yield per pass was 31.6% and acetylene yield per pass was 30.1% with 44.6% methane conversion at an input energy density of 1788kJ/mol and a pulse repetition frequency of 66Hz. The function of input energy density towards methane conversion may be expressed as a formula of -ln(1-X) = k (P/F). In the range of input energy employed, C-2 yield is proportional to input energy density, but energy efficiency drops off with increasing input energy density.

Effect of microstructural features on the fracture toughness of a welded alpha-beta TiAlMn alloy

The fracture toughness of weld fusion zones in a dilute, medium-strength alpha-beta TiAlMn alloy has been studied in relation to their microstructures. Welding was performed over a range of energy inputs using different techniques. The weldments were subjected to three different annealing treatments. It has been shown that the fracture toughness of all weld metals is greater than that of the parent material. The data also reveal that there is a further improvement in fracture toughness on postweld heat treatment. The results are discussed in terms of the structural changes occurring during welding and subsequent annealing.

Energy analysis of rape methyl ester (RME) production from winter oilseed rape

Energy ratios were calculated for production of the rapeseed-oil-based diesel substitute rape methyl ester (RME) from winter oilseed rape. The energy ratio of a biofuel can be defined as the ratio of the non-renewable energy used in its production to the energy value of the fuel and any utilised by-products, i.e. energy input:energy output. For each energy input and output, a range of energy values was calculated to account for different soil and weather conditions and variation in yield. In addition, the range of energy inputs calculated accounted for variation in published estimates of the amount of energy required for various processes. The range of inputs and outputs included values calculated for worst-case (i.e. lowest seed yield, highest pesticide applications, etc.) and best-case scenarios, and two intermediate values, which represented inputs and outputs expected under typical conditions in Scotland. From this data, energy ratios were calculated for rape methyl ester production under best-case, worst-case and intermediate scenarios, with and without the inclusion of by-products. The results indicated that RME production is sustainable under all but the worst conditions. Utilisation of rapemeal greatly improved the energy ratio, but there remained a net loss in energy under the worst-case scenario. Glycerol utilisation had relatively little effect on the energy ratio, while the use of straw resulted in a net energy gain from the production of RME under all scenarios.

Q-switched operation of a Nd:SGGM laser

A simmered Xe-gas filled flashlamp has been used to pump Nd 3+ ions doped in a SGGM rod in the free running, as well as Q-swiched, modes of operation for the first time. Laser output energies at 1.06 μm have been measured in the input energy range of 1–15 J. In the Q-switched mode of operation, the pulsed width has been measured to be about 50 ns (FWHM).

Relative performance of a 1.06 μm laser with various Nd doped crystals

Laser emission at 1.06 μm has been observed from Nd: doped YAG, KGW and SGGM crystals pumped by a linear Xe-gas filled flashlamp in the input energy range of 1–25 J. The intrinsic slope efficiency has been determined to be 8.84%, 2.25% and 1.25% from Nd: KGW (Nd: 3% atomic), Nd: YAG (Nd: 1.0% atomic) and Nd: SGGM (Nd: 4% atomic), respectively.

Near-resonant refractive nonlinearity in polydiacetylene 9-BCMU thin films

The spectral dependence of the third-order nonlinear susceptibility χ(3) (ω; ω, −ω, ω) of the polydiacetylene 9-BCMU has been measured, and the imaginary component is found to change sign in the exciton absorption tail. In the red-phase material, a significant refractive nonlinearity was observed around the 1.93-eV input energy range, whereas the absorption change was too small to quantify. A magnitude for the nonlinear refractive index coefficient |n2| = 1.9 (±1.0) × 10−10 cm2 W−1 was measured at this Im χ(3) = 0 position, indicating good figures of merit for all-optical switching.

Pulsed laser performance at 1.06 ?m from Nd:SGGM

A single Xe gas filled flash lamp has been used to pump a Nd-doped SGGM rod 5 mm in diameter and 80 mm in length. Laser emission has been observed at 1.06 μm in the free running mode of operation in the input energy range of 1–25 J. The laser performance has been evaluated using two different diffuse/filter combinations to block the ultraviolet radiation from the Xe lamp and the results have been compared. The intrinsic slope efficiency was determined to be approximately 1.5% with an 80% output coupler and a spectralon diffuser.

Optimized operation of short-pulse KrF amplifiers by off-axis amplification

A three-pass off-axis amplification scheme for subpicosecond pulses, producing 20 mJ output energy in a 20×22 mm 2 beam, with 10 6 energy contrast ratio is reported for a commercial excimer gain module. Calculations are performed showing this scheme capable of tailoring discharge-pumped gain modules to the needs of efficient short-pulse amplifications for a wide range of input energies.

All solid state copper vapor laser.

A copper vapor laser pumped with an all-solid-state switch modulator has been demonstrated forthe first time. The solid state switch modulator consists of static induction (SI) thyristors and twostage magnetic pulse compression circuits with saturable reactors. The maximum energy transferefficiency of the modulator was 67%. The modulator could work with high transfer efficiency over awide input energy range by optimization of the reset currents for saturable reactors. The averagelaser power was 21W at a 5kHz repetition rate.

Structure, properties and fracture of electron beam welds in RS-PM Al8FeMo

Electron beam welds were produced in rapidly-solidified, powder metallurgy (RS-PM) Al-8wt.%Fe-2wt.%Mo sheet using a range of energy inputs and metallurgically characterized with respect to microstructure, mechanical properties and fracture behavior. A reduction in the electron beam energy input required to produce autogenous, full-penetration welds and the associated increase in weld solidification and cooling rates were found to promote increasingly finer fusion zone microstructures comprising primary intermetallics and dendritic alpha aluminum (zone B type). Welds produced at the lowest energy inputs exhibited fusion zone hardnesses superior to that of the base metal, joint efficiencies exceeding 85% and acceptable ductilities. The use of a minimal energy input also prevented the formation of a structurally-coarsened region near the fusion boundary which served as the weak link in higher energy input weldments. Weld failure in this coarsened region was associated with delamination of the coarse intermetallic-alpha aluminum interfaces.

A study of the development of impact damage in cross-ply carbon fibre/PEEK laminates using acoustic emission

Instrumented falling weight impact tests were performed on [0/90] 10S laminates of carbon fibre/PEEK in order to investigate damage development. The specimens were afterwards subjected to four-point bending with acoustic emission monitoring (AE). In the impact tests a range of input energies were investigated (3·2 to 8·8 Joules) and it was observed that at 4·9 Joules the onset of delamination occurred. Ultrasonic C-scans of the impacted specimens confirmed this in a semi-quantitative manner. Replicate tests on other specimens also confirmed a delamination mechanism when they were sectioned for macroscopic examination with a dye-penetrant technique. In the bend tests this critical level of impact energy was associated with a sharp change in the evolution of AE under increasing load. At absorbed energies in impact, below that for the onset of delamination (4·9 Joules), the cumulative AE events count increased with load in the classical exponential manner. Above 4·9 Joules, where extensive damage was sustained, the exponential development at lower loads gave way, at a critical load, to a faster constant-rate evolution. This critical load, or displacement, which is defined as the ‘OCR’ point (Onset of Constant Rate AE), was dependent on the area of delamination damage in an inverse-type relationship. Bend tests on model specimens were performed in order to examine whether the transition in AE behaviour was associated with the relative movement between adjacent surfaces or the onset of crack growth at delaminations. Shorth-beam shear tests were also conducted in order to investigate the spread of crack in carbon fibre/PEEK, where little AE activity was observed up to an OCR point, which in turn coincided with the onset of shear delamination.

An experimental study of screw configuration effects in the twin-screw extrusion-cooking of maize grits

The effects of screw configuration on the product properties, die pressure and screw torque in the twin-screw extrusion-cooking of maize grits is described. Extrudate bulk density, water solubility and water absorption were measured for a set range of extrusion moisture contents and barrel temperatures for each of four screw configurations of different conveying efficiencies. It is shown that screw configuration is a potent variable in determining product properties. The variation in water solubility with specific mechanical energy input conforms to Meuser's model. The screw configuration controls the specific mechanical energy input range. Screw configurations of low conveying efficiency give rise to low-viscosity melts which expand into low-bulk-density products. Dead-stopped runs showed that the conveying efficiency controls the degree of fill in the extruder barrel. Typically, the mean residence time was increased from 56 to 94 s by decreasing the conveying efficiency of the screws.

Quadrature frequency conversion

A technique for frequency conversion of high-power lasers is described which uses two crystals for each conversion step rather than one. The two crystals are oriented so that the waves generated in them are orthogonally polarized. The conversion efficiency of these quadrature arrangements is much less sensitive to laser pulse nonuniformities than that in single-crystal methods. Consequently, very high conversion efficiency is possible for typically nonuniform laser pulses. Realization of the quadrature concept for all types of nonlinear optical processes are described. Data taken on second harmonic generation of Gaussian pulses shows that very high (internal) conversion efficiency is possible ( > 95 percent) over a substantial range of input energy.

Performance of a pickax

Single and multiple impact tests were conducted with a commerically available 3.58 kg pickax with a 60° conical tip and a 30° wedge tip in the input energy range from 1.01 to 59.4 J. Five target materials were employed: (1) 2024-0 aluminum, (2) diorite, (3) sandstone, (4) cement-sand, and (5) green shale. Force and penetration data were collected using strain gages and a non-contact displacement probe. It was found that when the impact process involves cracking and chipping, the maximum penetration was linearly proportional to the input energy and the forcepenetration relation exhibited non-linear characteristics. When the impact process does not involve cracking or chipping, the penetration was related to the square root of the input energy and the force-penetration relation exhibited a nearly linear relation. Thus, empirical models involving a linear spring resistive force or a constant resistive force were found to reasonably describe the penetration and input energy data. In addition, an analytical model involving a pickax mass inertia term and a piecewise linearized force-penetration function was constructed that portrayed the force and penetration histories. Good results were obtained for both conicaland wedge-tip cases. From the multiple impact tests it was found that the efficiency of the pickax operation decreases by about 50 to 60 percent after ten impacts, suggesting that the impact point be moved in order to obtain an improved performance.

Modification of thin film properties by ion bombardment during deposition

The modification of thin film properties by ion bombardment during deposition is reviewed, with the emphasis on broad-beam ion source techniques. Examples of property modification are given, including intrinsic stress modification, step coverage improvement, changes in preferred orientation, improved surface coverage, magnetic anisotropy control, improved epitaxy, crystal structure changes, modification of refractive index and optical transmission, and porosity reduction. The examples are displayed on a universal plot of the ion/atom arrival rate ratio vs the ion energy needed for property modification. The zone of ion bombardment parameters which causes these property changes spans a range of energy input from about 1 eV per depositing atom to several hundred eV per atom.

Developing a microprocessor-based energy management controller

This article is an account of a commercial study to develop a microprocessor-controlled water and space and water heating system. There are two control cycles, concerned with control of the source heating the transmission medium (water) and with the use of this heated medium according to the demands of the domestic environment. These control requirements are investigated in this article with a view to developing a system which would allow a range of energy inputs to be controlled and used.