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The energy distribution in electrical discharge machining is still subject to discussions. On the one hand, it is important to know the exact amount of energy that is applied to a workpiece, since solely this heat is responsible for the loads that are applied to the material and result in material modifications. On the other hand, it is very difficult to directly measure the heat due to the diminutive temporal and spatial scales. Hence, a method was developed to measure the size of the gas bubble that evolves during the discharge and used to model the energy fraction that dissipates during the formation of named bubble. With the easily measurable general energy input and the developed model, the number of unknown fractions of the energy distribution can be reduced. This step allows for a better assumption of the energies that load and modify the workpiece material.

As one of the most promising environmentally-friendly and renewable energies, biomass derived gas (BDG) has a great application prospect in the future energy system. Due to complex diversity of BDG components, the prediction of the important parameters, such as laminar flame speed, from the individual component will be realistic and reasonable than those from the direct measurement or calculation in some circumstances. In this study, existing mixing models are evaluated to predict the laminar flame speed of BDG. In addition, one-dimensional laminar premixed flame propagations are simulated to analyze flame temperatures and sensitivity coefficients of the laminar flame speed. For BDG with main components of CH4, H2 and CO, we employ the strategy that CH4 and H2 are mixed first and then wet CO is added into CH4/H2 mixture. For CH4/H2 blended fuels, flame-temperature-based and Le Chaterlier's models have the best fits for the laminar flame speed estimations of CH4/H2/air mixtures with lower and higher ZH2, respectively. Sensitivity analysis shows there are large discrepancy in chemical pathways for BDG with higher or lower ZCO and the laminar flame speed prediction of BDG will be conducted in two different circumstances. When CO ratio is lower than 0.85, Spalding rule and energy fraction method could predict the laminar flame speed best. For BDG with CO ratio larger than 0.85, Spalding rule and Chen's model are the best choices to predict the laminar flame speed of BDG.

This work experimentally examines the effect of methane (a natural gas surrogate) substitution on early injection dual fuel combustion at representative low loads of 3.3 and 5.0 bar BMEPs in a single-cylinder compression ignition engine. Gaseous methane fumigated into the intake manifold at various methane energy fractions was ignited using a high-pressure diesel pilot injection at 310 °CA. For the 3.3 bar BMEP, methane energy fraction sweeps from 50% to 90% were performed; while at 5.0 bar BMEP, methane energy fraction sweeps from 70% to 90% were performed. It is observed that minimum methane energy fraction is limited by maximum pressure rise rate leading to knock and maximum methane energy fraction is limited by a high coefficient of variation in netIMEP, which leads to high cyclic variations. For 3.3 bar BMEP, maximum pressure rise rate is 8 bar/°CA at 50% methane energy fraction while at 5 bar BMEP, it is 12 bar/°CA at 70% methane energy fraction. For 3.3 bar BMEP, engine-out NOx emissions decrease by 43 times when methane energy fraction increases from 50% to 90%, and it decreases by nearly 46 times when methane energy fraction increases from 70% to 90% at 5 bar BMEP. Engine-out unburned hydrocarbon emissions increase by nearly 9 times when methane energy fraction increases from 50% to 90% at 3.3 bar BMEP, and it increases by nearly 5 times when methane energy fraction increases from 70% to 90% at 5.0 bar BMEP. Engine-out carbon monoxide emissions increase by nearly 7 times when methane energy fraction increases from 50% to 90% at 3.3 bar BMEP and by nearly 5 times when methane energy fraction increases from 70% to 90% at 5.0 bar BMEP. In addition, cyclic combustion variations at both loads were analyzed to obtain further insights into the combustion process and identify opportunities to further improve fuel conversion efficiencies at low load operation.

After the war, there was a general understanding of reverberation time (RT), including how to measure it and its significance, as well as its link to a state of diffusion. Reverberation refers to a property of late sound; there was an appreciation that early sound must be significant, but in what way? Research had begun in the 1950s using simulation systems in anechoic chambers, with the Haas effect of 1951 being the most prominent result. Thiele’s Deutlichkeit, or early energy fraction, was important from 1953 and indirectly found expression in Beranek’s initial time delay gap (ITDG) from 1962. The 1960s produced a possible explanation for RTs in halls being shorter than calculations predicted, the importance of early sound for the sense of reverberation (EDT), the nature of directional sensitivity, conditions for echo disturbance, and the importance of early lateral reflections. Much of the research in the 1960s laid the foundations for research investigating the relative importance of the various subjective effects for concert hall listening. Important concert halls built during the period include Philharmonic Hall, New York (1962); Fairfield Hall, Croydon, London (1962); the Philharmonie, Berlin (1963); and De Doelen Hall, Rotterdam (1966). The parallel-sided halls of the past were rarely copied, however, due to architectural fashion. These various halls will be discussed as they make a fascinating group.

An electrical discharge forms a crater on the workpiece surface. The crater morphology estimates the performance parameters of the electrical discharge machining process. The energy parameters (gap voltage, discharge current and the pulse on time), the plasma channel radius and the energy fraction coming to the workpiece determine the molten cavity radius and depth. The plasma flushes away a portion of material from the molten cavity forming a crater and resolidification of the remaining molten material forms a recast layer. The plasma flushing efficiency determines the crater’s radius and depth. Few researchers have successfully expressed the plasma radius, energy fraction and plasma flushing efficiency in relation to two of the energy parameters, namely, discharge current and pulse on time but not as a gap voltage function. This work attempted to develop a thermo-physical model to express plasma radius, energy fraction and plasma flushing efficiency as a function of all three energy parameters, such as gap voltage, discharge current and pulse on time. Plasma flushing efficiency was calculated and plasma radius and energy fraction were estimated by inverse finite element method from the measured values of crater radius, crater depth and recast layer thickness. The expressions for plasma radius, energy fraction and plasma flushing efficiency were found out from the regression equations obtained from the designed data set using the Taguchi method. Validation shows that the modeled and experimental values of crater radius, crater depth, and recast layer thickness agree well.

In this study, acoustics of piri and daegeum, which are representative traditional Korean wind instruments, was investigated objectively and subjectively. The acoustic directivity patterns of piri and daegeum were measured in a full anechoic chamber. A subjective acoustic survey of piri and daegeum solo performances was conducted with 60 music students using an auralised concert hall with a volume of 18,838 m3. The sound produced by piri had extensive high-frequency harmonics and strong forward and downward directivity. In addition to a strong lateral and upward directivity, the sound produced by daegeum exhibited more explicit fundamental notes than those produced by piri. The reverberance, loudness, and envelopment of piri and daegeum were affected by early decay time (EDT), sound pressure level (SPL), and lateral energy fraction (LF80), respectively. The clarity of piri showed no explicit relationship with the clarity index (C80), but the clarity of daegeum was affected by the C80. Room acoustical conditions around a reverberation time of 2.6 s were preferred for the piri solo. However, for the daegeum solo, room acoustical conditions around a reverberation time of 1.7 s were preferred. The overall impression of piri was highly correlated with loudness and mid-treble balance. However, the overall impression of daegum did not show a strong linear correlation with other subjective attributes, such as piri (r > 0.6).

To determine an optimum combustion chamber design and engine operating strategies, computational fluid dynamics simulations of direct-injection spark-ignition engines have become an indispensable step in the powertrain development process. The laminar burning velocity of gasoline is known as an essential input parameter for combustion simulations. In this study, a new methodology for modeling the laminar burning velocity of gasoline for direct-injection spark-ignition engine simulations is proposed. Considering the gasoline as a complex mixture of hydrocarbon fuel, three hydrocarbons, iso-octane, n-heptane, and toluene were incorporated as surrogate fuel components to represent gasoline with distinct aromatic laminar flame characteristics compared to alkane. A mixing rule, based on energy fractions, was adopted to consider the compositional variation of gasoline. The laminar burning velocities of iso-octane, n-heptane, and toluene were calculated under wide thermo-chemical conditions in conjunction with detailed chemical reaction kinetics in the premixed flame simulation. Finally, a set of laminar burning velocity model equations was derived by curve-fitting the flame simulation results of each hydrocarbon component in consideration of the effect of temperature, pressure, and diluent. The laminar burning velocity model was validated against the measurement data of gasoline’s laminar burning velocity found in the literature, and was applied to the computational fluid dynamics simulation of a direct-injection spark-ignition engine under the various operating conditions to explore the prediction capability.

Latent thermal energy storage heat exchangers have a large potential in different processes. Implementing such a heat exchanger requires evaluating the performance of the heat exchanger in the conditions of each specific process. Therefore a method to characterize the performance of a latent thermal energy storage design would be a useful tool for designing processes. Characterization methods for heat exchangers such as the effectiveness number of transfer units method are based on the steady-state operation of the heat exchanger. However, latent thermal energy storage heat exchangers do not operate in steady state and therefore the standard methods are not applicable. The present paper develops a novel method to determine the heat transfer fluid outlet state as a function of the initial and input conditions: the charging time energy fraction method. This method is used to characterize and evaluate a latent thermal energy storage channel heat exchanger. For 26 out of 30 calibration and validation experiments, the model predicts the outlet heat transfer fluid temperature within measurement uncertainty (±0.15 °C) during all but the initial 100 s of the charging process. The charging time energy fraction method is according to the authors the first approach to derive a predictive, low computational cost model of the outlet temperature of a latent thermal energy storage heat exchanger from a set of experiments.

In several auditoria, it has been observed that the reverberation time is longer than expected and that the cause is a horizontal reverberant field established in the region near the ceiling, a field which is remote from the sound absorbing audience. This has been observed in the Boston Symphony Hall, Massachusetts, and the Stadthalle Gottingen, Germany. Subjective remarks on their acoustics suggest that there are no unfavourable comments linked to the secondary sound field. Two acoustic scale models are considered here. In a generic rectangular concert hall model, the walls and ceiling contained openings in which either plane or scattering panels could be placed. With plane panels, the model reverberation time (RT) was measured as 53% higher than the Sabine prediction (frequency 500/1000 Hz), compared with 8% higher with scattering panels. The second model of a 300 seat lecture theatre with a 6 m or 8 m high ceiling had raked seating. In this case, the amount of absorption in the model was increased until the point was reached where speech had acceptable intelligibility, with the early energy fraction, D ⩾ 0.5. For this acceptable speech condition with the 6 m ceiling, the measured mid-frequency T 15 was 1.47 s, whereas the Sabine predicted RT was 1.06 s. The sound decay was basically non-linear with T 30 > T 15 > EDT. Exploiting a high-level horizontal reverberant field offers the possibility of acoustics that are better adapted as suitable for both speech and unamplified music, without any physical change in the auditorium. Using secondary reverberation in an auditorium for a wide variety of music might also be beneficial.

According to the entropy theory, the increase in the thermodynamic entropy of energy is reduced under the control of the information entropy. However, the quantitative analysis of this process remains difficult. In this study, energy properties are conferred upon information to enable an uncertain event to be measured. First, the entropy theory was adopted to describe the uncertainty of the energy in a distributed energy system. Further, a method was devised to optimize the configurations of the distributed energy system based on minimize total entropy generation. Finally, using the example of load forecasting, the impact of introducing information in the form of negative entropy on the ability of the system to improve the alignment between supply and demand is quantitatively elucidated. The negative entropy caused by information utilization increased from 356.14 to 638.68 kWh/K, with the load forecasting errors decreased from 30% to 10%. The information entropy was also applied to describe the uncertainty of the On-site energy fraction, by increasing the capacity of energy storage, the uncertainty decreased from 1.81 to 1.80 nat, while the load forecasting could decreased it to 1.71 nat, 1.54 nat, 1.29 nat with the load forecasting errors at 30%, 20% and 10%, respectively.

The plug flow was investigated in both the single plug and the continuous plug experiments. In the single plug flow, the pressure drop might rise for two times with a longer plug, and the second increase was proved to be caused by the collision between the falling particles and the plug by acoustic emission detection. In continuous plug flow, the interaction between the bulk of the plug and the pipe wall was dominated by the friction. And the sources of acoustic signals in continuous plug flow can be mainly divided into two parts: the collision between the falling particles and the plug and the friction between the bulk of plug and the wall. Based on this, the acoustic model was derived and the energy fraction can be predicted accurately. And the model further provides a possibility for the non-intrusive, real-time and online detection of Janssen coefficient.

The prediction of single-spin asymmetry in inelastic photoproduction of $J/\ensuremath{\psi}$ in $e{p}^{\ensuremath{\uparrow}}$ collision is presented. At next-to-leading order, the dominating process is photon-gluon fusion, $\ensuremath{\gamma}+g\ensuremath{\rightarrow}J/\ensuremath{\psi}+g$ for the production of $J/\ensuremath{\psi}$ in $e+{p}^{\ensuremath{\uparrow}}\ensuremath{\rightarrow}J/\ensuremath{\psi}+X$, which directly probes the gluon Sivers function. Using the nonrelativistic QCD based color octet model, the color octet states ${^{3}S}_{1}^{(8)}$, ${^{1}S}_{0}^{(8)}$ and ${^{3}P}_{J(0,1,2)}^{(8)}$ contribution to $J/\ensuremath{\psi}$ production is calculated. Sizable asymmetry is estimated as a function of transverse momentum ${P}_{T}$ and energy fraction $z$ of $J/\ensuremath{\psi}$ in the range $0l{P}_{T}\ensuremath{\le}1\text{ }\text{ }\mathrm{GeV}$ and $0.3lz\ensuremath{\le}0.9$. The unpolarized differential cross section of inelastic $J/\ensuremath{\psi}$ photoproduction is found to be in good agreement with H1 and ZEUS data.

Capturing stereophonic room impulse responses for simulation of spatial impression of an acoustic space, for example for music production, is time consuming and expensive, especially when large database of well-recognized music spaces is needed. However, these spaces are often measured by companies dealing with room acoustics in order to compare their objective listening quality. The paper presents method for obtaining stereophonic room impulse responses from room impulse responses captured in order to compute some criteria of objective evaluation of acoustic spaces.

Track-assisted mass is a proxy for jet mass that only uses direction information from charged particles, allowing it to be measured at the Large Hadron Collider with very fine angular resolution. In this paper, we introduce a generalization of track-assisted mass and analyze its performance in both parton shower generators and resummed calculations. For the original track-assisted mass, the track-only mass is rescaled by the charged energy fraction of the jet. In our generalization, the rescaling factor includes both per-jet and ensemble-averaged information, facilitating a closer correspondence to ordinary jet mass. Using the track function formalism in electron-positron collisions, we calculate the spectrum of generalized track-assisted mass to next-to-leading-logarithmic order with leading-order matching. These resummed calculations provide theoretical insight into the close correspondence between track-assisted mass and ordinary jet mass. With the growing importance of jet grooming algorithms, we also calculate track-assisted mass on soft-drop groomed jets., 35+17 pages, 22 figures; v3: improvements to calculation and presentation to appear in JHEP

Primordial black holes can be produced by a long range attractive fifth force stronger than gravity, mediated by a light scalar field interacting with nonrelativistic "heavy" particles. As soon as the energy fraction of heavy particles reaches a threshold, the fluctuations rapidly become nonlinear. The overdensities collapse into black holes or similar screened objects, without the need for any particular feature in the spectrum of primordial density fluctuations generated during inflation. We discuss whether such primordial black holes can constitute the total dark matter component in the Universe., Comment: 6 pages, 1 figure, published version, added clarifications and references, corrected typos

We present the observations with the MAGIC telescopes of SN 2014J, which correspond to the first results in the very-high-energy (VHE; E > 100 GeV) gamma-ray regime of a Type Ia Supernova (SN). The source was observed 6 days after the explosion for a total of ∼ 6 hours. No significant excess was found and hence, upper limits (ULs) at a 95% confidence level (CL) were computed. We constrain the energy fraction emitted into VHE gamma rays during the first days and provide prospects for gamma-ray emission in the near future.

Previously established and validated coal combustion model in a circulating fluidized bed (CFB) was employed to predict co-combustion of lignite and biomass processes. The validity of the model was successfully performed on a large-scale 261 MW e COMPACT CFB boiler. Forest biomass, sunflower husk, willow and lignite coal were applied in co-combustion tests with different shares of biomass and lignite. The energy fraction of biomass in fuel blend was: 7%, 10% and 15%. Emissions of CO 2 , CO, SO 2 and NO x (i.e., NO + NO 2 ) from the co-combustion tests, measured during experiments and predicted by model were compared. The gaseous pollutant emissions, evaluated using the developed model were in a good agreement with experimental results.

Models for shock initiation in explosives must consider how energy transfers from products to reactants. This is based on different energy-apportionment assumptions, which affect the results for shock initiation. This study proposes a robust model of shock initiation in explosives using a free choice of energy-apportionment assumptions. The reacting explosive is treated as a mixture of reactants and products under different energy-apportionment assumptions. The equations of state of the mixture are efficiently solved by refining the Cochran–Chan concept of the real volume fraction and introducing a real energy fraction term. The validity, efficiency, and universality of the proposed model are verified in one-dimensional numerical simulations of the shock initiation of homogeneous (nitromethane) and heterogeneous (PBX 9404) explosives. Compared to the conventional Cochran–Chan and Johnson–Tang–Forest models, the proposed model has a better balance of computational efficiency and universality.

The purpose of this study was to evaluate the measurement deviations of the spatial measures lateral energy fraction (LF) and late lateral energy level (GLL), obtained using figure-of-eight microphones. The following factors that may contribute to measurement deviations were evaluated: (1) microphone orientation, (2) spacing between figure-of-eight and omni-directional microphones, which varied from 64 to 152 mm, and (3) differences between individual microphones. Impulse response measurements were taken in a 100-seat lecture hall at four receiver positions using a total of eight figure-of-eight microphones. The average differences due to microphone orientation and spacing, were found to be relatively small: 0.20 ± 0.18 dB (4.3 ± 3.8%) for GLL and 0.02 ± 0.02 (2.0 ± 2.4 JNDs) for LF. (The just noticeable difference (JND) of LF has been established at 5%, however the GLL JND has not yet been established.) The largest differences were found when comparing the results between the individual microphones with differences on the order of 0.92 ± 0.73 dB (16 ± 13%) for GLL and 0.022 ± 0.018 (2.6 ± 1.9 JNDs) for LF. These larger differences are likely due to the variations in microphone sensitivity. Based on the measurement conditions used in this case study, it is possible to compare GLL and LF measurements with a given figure-8 microphone in order to evaluate relative differences, since the measurement deviations for a given microphone were found to be relatively low. However, it is difficult to compare the results of data obtained using different figure-8 microphones due to the measurement deviations of the microphones.

Computer simulations to predict acoustical parameters have been attracting renewed interest in recent years. This paper reports the results of computer simulations of the acoustics of box-shaped churches. Twenty-five buildings have been considered by varying the dimensional ratios between length, width and height. The study focuses on the values assumed by three acoustical parameters, the clarity, the early lateral energy fraction and the centre time, in each of the simulated buildings. The parameters of analysis allowed to evaluate the dependence between the shape of the building and its acoustics. Moreover, in each church, simulations were realized by moving the sound source in five different positions in order to investigate how the acoustics changes. Considering the trade-off among dimensional ratios of the room, volume and source position, formulae which predict acoustical parameters in box-shaped churches are presented. A first validation of these formulae has been made using measured acoustical par...

Objective parameters for the evaluation of the Rudolfinum concert hall in Prague, Czech Republic are the focus of the present article. The measured results for Reverberation parameters, Energy parameters, Intelligibility parameters, and Spatial parameters of the building’s two halls are presented and discussed including a comparison with recommended values or theory, as well as several unique architectural and acoustical qualities of the halls. The early lateral energy fraction parameter is measured by the intensity probe method discussed in the supplement. The performance is verified by tests in anechoic and reverberant rooms.

Production of the doubly heavy-flavored hadrons (${B}_{c}$ meson, doubly heavy baryons ${\mathrm{\ensuremath{\Xi}}}_{cc}$, ${\mathrm{\ensuremath{\Xi}}}_{bc}$, ${\mathrm{\ensuremath{\Xi}}}_{bb}$, their excited states, and antiparticles of them as well) at ${e}^{+}{e}^{\ensuremath{-}}$ colliders is investigated under two different approaches: LO (leading-order QCD complete calculation) and LL (leading-logarithm fragmentation calculation). The results for the production obtained by the LO and LL approaches, including the angle distributions of the produced hadrons with unpolarized and polarized incoming beams, the behaviors on the energy fraction of the produced doubly heavy-flavored hadron, and comparisons of results between the two approaches, are presented in tables and figures. Thus, characteristics of the production and uncertainties of the approaches are shown precisely, and it is concluded that only if the colliders run at the energies around the $Z$ pole (which may be called the $Z$ factories) and the luminosity of the colliders is as high as possible is the study of the doubly heavy-flavored hadrons completely accessible.

Shrinkage-reducing admixtures (SRAs) are used to reduce the shrinkage of concrete, whether from drying or self-desiccation. In contrast to other concrete admixtures, they are used in rather large amounts. This is because the interfacial area at which they must act (liquid–vapor) increases radically in the course of drying. Indeed, hardened cementitious materials have large internal surface area, which when covered only by liquid films, provides a very large interfacial area where the SRAs must remain active. More detailed considerations concerning the working mechanisms of these admixtures have been developed by examining the Helmholtz free energy. In this chapter, it is shown that the energy made available by drying is used in two processes: deformation and creation of interfacial area. SRAs increase the energy fraction used in the creation of interfacial by reducing the surface tension of the liquid–vapor interface. It directly follows that less energy is available for deformation and shrinkage is reduced.

Dimethyl ether (DME) and methanol are thought to be one of the most promising alternative fuels for IC engines. Meanwhile, previous investigations also have pointed out the good prospects for adopting DME and methanol in IC engines. The experiments in this paper were carried out at idle condition to investigate the effect of applying the methanol/DME blended fuel in a SI engine. The engine was modified to be fueled with the mixture of methanol and DME which were injected into the engine intake ports simultaneously. Various DME fractions were selected to investigate the effect of DME addition on engine performance. The experimental results showed that indicated thermal efficiency was increased by 25% and coefficient of cyclic variation in engine speed was decreased by 29.2% at the DME energy fraction of 85.2% in the total fuel. In addition, both flame development and propagation durations were shortened with the increase of DME enrichment level at idle condition. Meanwhile, the largest drop of HC emissions was nearly 50% compared with the original methanol engine at stoichiometric condition. However, CO and NOx emissions increase with the addition of DME.

Normally, the main generators of microgrid system use controllable energy resources such as fossil fuel, biomass, biogas, hydro, etc for uncomplicated control. However, it is very challenging to control the microgrid system that uses uncontrollable energy resources such as solar and wind for main generators of microgrid system because they have many advantages. From this point, the PV microgrid system is constructed and operated at School of Renewable Energy Technology (SERT), Naresuan University for research and development of the microgrid system that is supplying 50% of total electricity demand by PV main generator. By measuring the important parameters such as solar irradiance, PV array voltage, PV array current, and AC electrical power, these data were collected for a year from November 2008 to October 2009 to use in evaluation processes. The PV generator evaluation result is revealed that the average reference yield (Yr), array yield (YA), and final yield (Yf) are 5.21, 4.32, and 3.84 kWh/kWp day respectively. The average total loss of the PV generator is 26.27% that comes from summing up the average capture losses (LC) 17.21% and average system losses (LS) 9.06%. The average overall PV plant efficiency (ηtot) is 10.41%, and the average performance ratio (PR) is 73.45%. While considering the system efficiency of the PV generator at various solar irradiance, we found that it has the lowest efficiency when the solar irradiance is in the range 0 - 0.10 kW/m2, its efficiency increases with the increasing in the solar irradiance from 0.10 to 0.35 kW/m2, the efficiency becomes highest when the solar irradiance in the range of 0.35 to 0.65 kW/m2, and its efficiency decreases slowly when the solar irradiance is in the range of 0.65 to 1.30 kW/m2. For energy supplied fraction of the microgrid, it can achieve the PV generator producing target by PV generator and external grid supplying 73% and 27% of the total load of the microgrid.

We study J/Ψ inclusive production in the decays of P-wave bottomonium χbJ(1P, 2P) for J = 0,1,2. Within the framework of the non-relativistic QCD (NRQCD) factorization method we calculate the contributions coming from four relevant processes including one color-singlet process and three color-octet ones, which are and . Our calculation shows that the color-octet processes, especially the gluon fragmentation one, contribute the most in the decays of χb0 and χb1. However, the J/Ψ production in the χb2 decay is dominated by the color-singlet process. Furthermore, the gluon fragmentation process gives a δ function in the energy fraction distribution of J/Ψ, which can be considered to be another characteristic for its identification. From our estimation the branching ratio for these processes is about 10−4 – 10−5, which indicates that J/Ψ inclusive production is detectable at B-factories. Studying these processes would help us to gain a deeper understanding of the color-octet mechanism.

Several modeling approaches have been attempted to characterize the electrical discharge machining (EDM) process based on electro-thermal concepts. However, each model has varied characteristics and approximation results. It is important to elucidate the differences of each model and their proximity to the real material removal process. In this paper, five EDM models from Snoeys, Van Dijck, Beck, Jilani, and DiBitonto are analyzed in terms of the temperature distribution, crater geometry, and material removal at the cathode. Comparative analyses on the material removal rate (MRR) ratio of the predicted result to experimental data for discharge energy range from 0.33 to 952 mJ showed that DiBitonto's model yielded the closest proximity of 1.2–46.1 MRR ratio. This is followed by Jilani (2–45.9 MRR ratio), Snoey (3.9–203.2 MRR ratio), Beck (4.9–197.7 MRR ratio), and Van Dijck (26.8–1399 MRR ratio). This paper also shows that the disk heat source models can be enhanced by improving the approximation of the heat flux and energy fraction.

Final state interactions in quark fragmentation may give origin to non zero values of the off-diagonal element rho_(1,-1) of the helicity density matrix of vector mesons V produced in current jets, with a large energy fraction x_E; the value of rho_(1,-1)(V) is related to the hard constituent dynamics and tests unusual properties of it. Some recent data on phi, K^* and D^* produced in e^+ e^- annihilations at LEP show such effects. Predictions are given here for rho_(1,-1) of heavy mesons produced in nucleon-nucleon, gamma-nucleon and lepton-nucleon interactions., Comment: LaTeX, 10 pages, 1 postscript figure, uses epsfig.sty. Revised version, to be published on Phys. Lett. B. Some statements added to clarify text

The problem of evaluating the subjective acoustical quality of a performance space through studying the value of measurable acoustical parameters is yet to be fully solved. As a contribution to its solution this paper aims to determine whether any relationships exist between the various acoustic parameters most often considered. The acoustical parameters that are topical for this study are in the number of three. The first of these parameters is the Inter-Aural Cross-Correlation Coefficient (IACC), which is a measure of the diffuseness of the sound field in the room. Then the Early Lateral Energy Fraction (ELEF), or a related measure, the Spaciousness (S), is used for estimating the relative amount of early sound energy reaching the listener from lateral incidence. And lastly the Initial Time Delay Gap (ITDG), which is a temporal factor and an indicator of the rapidity of early echoes for contributing to the early signal build-up at following the direct signal. For the evaluation of these paramet...

It has been empirically recognized that high-frequency components of S waves radiated from earthquake do not show a radiation pattern predicted from a double-couple source, while the low frequency components show the standard double-couple radiation pattern. In this paper, we investigate this frequency dependence of radiation pattern using the high quality single-station records from the aftershock events of the 26 March 1997 and 13 May 1997 Northwestern Kagoshima, Japan, earthquakes. We focus on frequency dependence of energy partition between SH and SV waves in the direct S-phase. From the variation of the SH energy fraction with frequency we find that the energy fraction can be well predicted by theoretical radiation coefficients for a double-couple source at frequencies lower than 2 Hz, while at 3.5 Hz or higher it cannot be predicted and shows stochastic behavior. The intermediate frequencies can be seen as a transition from deterministic to stochastic. This supports the assumption that the radiation patterns of SH and SV waves are purely stochastic for high frequencies. Analyses of events which are located close to each other suggest that this stochastic nature is ascribed to strong SH and SV mixing or coupling induced by local structural effects near the sources.

The development of the shower induced by 26- and 28-GeV electrons in the oriented tungsten crystal results in strong absorption of the shower energy by the crystal and an increase in the energy fraction of shower particles scattered between the crystal and detector. The ratios of total shower energy losses in oriented tungsten crystals to total losses in misoriented crystals 1, 2.7, 5.8, and 8.4 mm thick were 3.9, 2.6, 2.1, and 1.9, respectively.

In room acoustics, several measures have been defined that are supposed to quantify the apparent source width (ASW) in a hall, being one of the perceptual cues related to spaciousness. The most common ones are the lateral energy fraction (LF), i.e., the ratio between lateral and omnidirectional early energy, and the interaural cross correlation coefficient (IACC), all to be calculated from measured or simulated impulse responses. [Several versions of the LF are known in literature, having different names, generalized here as lateral energy fraction.] According to a method proposed by Berkhout et al. [J. Acoust. Soc. Am. 102, 2757–2770 (1997)], for a fixed source position impulse responses have been measured along an array of closely spaced microphone positions in several halls. The above measures, when calculated from these impulse responses, show large fluctuations with small variations in microphone position due to interference of the different components of the wave field to which the human ear is apparently insensitive. A revision of the measures is discussed, which contributes to the suppression of the interference effects. In order to assess their perceptual significance, the fluctuations have to be related to just-noticeable differences (jnd’s) in ASW. Since very different jnd values are given in the literature, the authors advise that new experiments should be conducted on this point.

A method of predicting the G values (the strength factor in dB), C 80 values (the clarity factor in dB) and LF (the lateral energy fraction) in concert halls has been investigated. Constructional and acoustical data for 72 unoccupied concert halls, in various countries, were utilized for the neural network analyses. One source in two positions, in 42 of the halls, one source in three positions, in 13 of the halls, and a single source in 17 of the halls were chosen, together with a combination of receiver positions were available to train the neural networks. In all cases, the source used was omnidirectional. Results show that for the position-dependent strength factor, G , the accuracy of the neural network predictions is within the subjective difference limen, which is 1 dB. (i.e. Δ E / E =0.26 where E is energy density). Results also showed that the accuracy of neural network predictions for the clarity factor, C 80 , and the lateral energy fraction, LF , are within the subjective difference limens of ±0.5 dB and ±0.05, respectively. Eight concert halls were used to assess the neural network analysis method — by comparing neural network predictions with measured values and with predictions using Barron’s revised theory. In addition, three of the eight halls were used to compare neural network results with those obtained using by the hybrid ray tracing computer model ODEON 4.01. The results indicate that there is a good basis for using trained neural networks to predict the acoustical attributes G , C 80 and LF at the schematic stage.

In concert hall acoustics, spatial perception is a crucial element of the experience, yet several questions remain unresolved. In the 1960s, there was some work on what was then called ‘room impression’ caused by diffuse reverberation. The possible importance of early lateral reflections was proposed in 1967 by Marshall [Marshall AH. A note on the importance of room cross-section in concert halls. Journal of Sound and Vibration 1967;5:100–12] and until recently concern for the effect of early reflections has overshadowed study of the spatial effects linked to the later sound. Bradley and Soulodre [Bradley JS, Soulodre GA. The influence of late arriving energy on spatial impression. Journal of the Acoustical Society of America 1995;97:2263–71; Bradley JS, Soulodre GA. Objective measures of listener envelopment. Journal of the Acoustical Society of America 1995;98;2590–7] have now suggested that early reflections are predominantly responsible for creating a sense of source broadening [and apparent source width (ASW)], whereas a sense of envelopment, which had on occasions been linked to ASW, is almost solely produced by later lateral reflections. Bradley and Soulodre have proposed the late lateral energy level as a measure of listener envelopment (LEV). This paper considers some of the history of spatial perception in concert halls and reports on measured results made in 17 halls of the late lateral energy fraction (LLF) and the late lateral energy level (GLL). The spread of measured values of LLF turned out to be small and GLL was found to be predominantly determined by the total acoustic absorption of halls.

In the 30 years since early lateral reflections were first suggested as important for concert halls, spatial impression and source broadening have become almost universally accepted as essential characteristics of halls with good acoustics. Two objective measures of source broadening have been proposed. Measured values of the best defined of these measures, the early lateral energy fraction (LF), are considered here. Results from two independent measurement surveys are discussed. Comparisons of LF values by hall show a significant link between hall mean LF and hall width. There is however considerable overlap between measured LF values in different halls so the relevance of describing halls by their mean early lateral energy fraction values is questionable. The behaviour of LF values within auditoria is discussed for different concert hall plan forms and within opera houses. A measure of source broadening including sound level is proposed and results considered in the context of auditorium design.

Auditory spaciousness is primarily dependent on the strength of early lateral energy. The difference between the degree of spaciousness caused by only lateral reflections and that caused by lateral and ceiling reflections, however, has not been definitively clarified yet. In this paper, a series of psycho-acoustical experiments is performed to examine the effect of early reflections from upside on spaciousness with lateral reflections. The results show that a single reflection from upside causes a vertical spread of sound image and auditory envelopment becomes stronger as vertical component of reflected energy increases when lateral energy fraction and listening level are constant.