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Studying the macroscopic‐phenomenological behavior of amorphous polymers at glass transition is often subject to limitations because the ordinary differential equations that describe the material behavior require numerical solution. To avoid these limitations, ad‐hoc‐formulated models of the glass transition have been proposed. However, their scope of application is expected to be limited due to insufficient theoretical foundation. This work establishes a theoretical framework for models that use the logistic function to approximate the macroscopic‐phenomenological behavior of amorphous polymers at glass transition. For this purpose, an exactly‐solvable Riccati equation is derived within thermodynamics with internal state variables. A closed‐form expression in terms of mathematical functions for the temperature derivative of a single internal state variable is the result. This closed‐form expression contains the logistic function thus featuring a continuous transition region centered around a pressure and cooling‐rate dependent transition temperature. Based on comparison of existing models with the exact solution derived from the Riccati equation, generalized models that approximate the thermal expansion coefficient and heat capacity at glass transition are proposed. This work thus demonstrates the validity of the logistic function in glass transition models of amorphous polymers and provides suggestions as to how existing models can be extended in their applicability. [ABSTRACT FROM AUTHOR]

Plasma actuators used for active flow control are widely studied because they could replace mechanical actuators. Industrial applications of these plasma actuators sometimes require a large surface plasma sheet in view of increasing the interaction region between the discharge and the incoming flow. Instead of using a typical two-electrode nanosecond pulsed dielectric barrier discharge for which the interaction region is limited to about 20 mm, this study proposes to characterize a nanosecond sliding discharge based on a three-electrode geometry in order to increase the extension length up to the electrode gap. This sliding discharge is compared to the typical nanosecond dielectric barrier discharge by means of electrical, optical, and mechanical diagnostics. Electrical characterization reveals that the deposited energy can be widely increased. Time-resolved Intensified Charge Coupled Device (iCCD) images of the discharge development over the dielectric surface highlight that the intensity and the propagation velocity of streamers are strongly affected by the DC voltage applied at the third electrode. Finally, qualitative and quantitative characterizations of the pressure wave due to the surrounding gas heating are proposed by means of Schlieren visualizations and high frequency pressure measurements, respectively. [ABSTRACT FROM AUTHOR]

Using a diamond anvil cell, the evolutions of alternate-current impedance spectra and direct- current resistivity in B12As2 have been investigated up to 51.9 GPa. The results provide evidence for the existence of grain and grain boundary effects that are separated in the frequency region. The grain boundary resistance shows a relatively smaller contribution to the total resistance above 16.8 GPa. By using the double-Schottky barrier model, the space charge potential was obtained. A pressure-induced inversion of charge defect concentration in the space charge layer was found at 20.7 GPa. The high-temperature resistivity measurements indicate that the transport activation energy is determined by defect energy levels in the band gap. [ABSTRACT FROM AUTHOR]

Considering the phonon-phonon interactions, we obtain the high temperature phonons of Mo under high pressure. The dynamically stable regions of bcc and fcc Mo in the phase diagram are predicted. By comparing the anharmonic free energy, we determine the bcc-fcc boundary. The bcc Mo is the stable phase up to 700 GPa. Around 210 GPa, there is no bcc-fcc phase transition, which is different with the results from quasiharmonic approximation. [ABSTRACT FROM AUTHOR]

In large explosive and propellant charges, relatively low shock pressures on the order of 1-2 GPa impacting large volumes and lasting tens of microseconds can cause shock initiation of detonation. The pressure buildup process requires several centimeters of shock propagation before shock to detonation transition occurs. In this paper, experimentally measured run distances to detonation for lower input shock pressures are shown to be much longer than predicted by extrapolation of high shock pressure data. Run distance to detonation and embedded manganin gauge pressure histories are measured using large diameter charges of six octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) based plastic bonded explosives (PBX's): PBX 9404; LX-04; LX-07; LX-10; PBX 9501; and EDC37. The embedded gauge records show that the lower shock pressures create fewer and less energetic "hot spot" reaction sites, which consume the surrounding explosive particles at reduced reaction rates and cause longer distances to detonation. The experimental data is analyzed using the ignition and growth reactive flow model of shock initiation in solid explosives. Using minimum values of the degrees of compression required to ignite hot spot reactions, the previously determined high shock pressure ignition and growth model parameters for the six explosives accurately simulate the much longer run distances to detonation and much slower growths of pressure behind the shock fronts measured during the shock initiation of HMX PBX's at several low shock pressures. [ABSTRACT FROM AUTHOR]

Highlights • A multiscale micromechanical homogenization framework is proposed for fluid-filled porous materials. • The overall elastic properties of the fluid-filled porous materials are determined in the framework. • The effects of pore distribution and fluid pressure on the effective elastic properties are quantified. • By considering the fluid diffusion from macro- to micro-scale pores, evolution of the effective properties is predicted. Abstract Fluid-filled porous materials are widely encountered in natural and artificial systems. A comprehensive understanding of the elastic behavior of such materials and its dependence on fluid diffusion is therefore of fundamental importance. In this work, a multiscale framework is developed to model the overall elastic response of fluid-filled porous materials. By utilizing a two-dimensional micromechanical model with porosity at two scales, the effects of fluid diffusion and the geometric arrangement of pores on the evolution of effective properties in fluid-filled porous materials are investigated. Initially, for a single-porosity model the effective elastic properties of the dry and fluid-filled porous materials with ordered pores are obtained theoretically by considering a geometrical factor, which is related to the distribution of pores in the matrix. Model predictions are validated by finite element simulations. By employing a double-porosity model, fluid diffusion from macro- to micro-scale pores driven by a pressure gradient is investigated, and the resulting time-dependent effective elastic properties are obtained for both constant pressure and constant injection rate conditions. It is found that the presence and diffusion of pressurized pore fluid significantly affect the elastic response of porous materials, and this must be considered when modeling such materials. It is expected that the proposed theoretical model will advance the understanding of the fluid-governed elastic response of porous materials with implications towards the analysis of geophysical, biological and artificial fluid-filled porous systems. Graphic abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Highlights • CO 2 huff 'n' puff process study on CO 2 storage and enhance heavy oil recovery. • A novel equation to predict relation between CO 2 and heavy oil production. • A new terminology is defined to analyze the production performance. • The soaking time and pressure depletion rate are optimized and upscaled. Abstract In order to study a potential way to store CO 2 and enhance heavy oil production performance, five experiments are implemented on the CO 2 huff 'n' puff process using long cores. The production profiles of the CO 2 huff 'n' puff process are analyzed, including pressure, heavy oil recovery factor, gas production, cumulative gas oil ratio, and pressure difference. The pressure drops indicate the CO 2 diffusion in heavy oil. The pressure drop in the first cycle is much lower than those in the subsequent cycles. The heavy oil recovery factor is higher than 32.75% and can reach as high as 38.02% under the pressure depletion rate of 1 kPa/min. A main trend observed for each test is that the heavy oil recovery factor decreases with increases in the cycle number. With oil production, a growing space is available for CO 2 injection in the core, resulting in a higher volume of injected CO 2 together with increasing gas production and a cumulative gas oil ratio. With less heavy oil production, the pressure difference between the end port and the production port decreases with the cycle number increases. A novel equation is developed to study the relationship between CO 2 production and heavy oil production, and the agreement between the equation and the experimental data is extremely high ( R 2 > 0.97). This novel equation can be applied to predict the production performance in the later production period in the same cycle and/or to predict the performance in the subsequent cycles. Via the analyzation of the production performance of the CO 2 huff 'n' puff process in heavy oil under different pressure depletion rates and different soaking times, the effect parameters, including pressure depletion rates, soaking time and cycle numbers, are optimized in this study. The optimized pressure depletion rates, soaking time, and cycle numbers are 1 kPa/min, 5 h and 3 cycles, respectively. The optimized parameters gained in the tests were upscaled using the scaling criteria, and the upscaled parameters can be applied in the field pilot test to enhance heavy oil recovery using the CO 2 huff 'n' puff process. [ABSTRACT FROM AUTHOR]

Objectives The characteristics of dye laser such as purity, concentration and dye solvent velocity have significant effects on the output power of laser. The main objective was to investigate the effects of the dye solvent velocity on the laser output power. Methods/Statistical analysis A homemade ring dye laser (Rhodamine 6G) was used and the liquid dye was injected by a liquid jet and pumped by beam of a 6 W argon ion laser (λ = 488 nm). By using mechanical pumping, the liquid pressure was controlled and different velocities were selected. Findings It was observed that by increasing the pressure, the output power of dye laser, was increased initially and then in a certain pressure variation region (0.65–0.69 MPa), some slight changes were detected. By increasing more dye liquid pressure, the laser output was decreased considerably. The maximum output laser power obtained in a wavelength ranges within 5702–6072 Å, was approximately 140 mW. It was seen that by increasing the pumping power, the dye laser output power was increased. Moreover, for each specific wavelength, there was a threshold power (in pumping laser) for dye laser emission in order to be initiated. For example for the laser emission at 5763 Å and 5990 Å, the minimum pumping laser powers are ~4.1 and 5.2 W, respectively. Dye solvent velocity in output power of dye laser is not appropriately discussed in previous studies, so it can be stated that in the current study, it was carried out with different conditions. Application/Improvements Applying suitable dye solvent velocity is one of the important issues in designing ring dye laser that has been correctly discussed and utilized in the current study. [ABSTRACT FROM AUTHOR]

One of today's challenges in reservoir management of liquid-rich shales is to accurately forecast production performance based on pressure/rate transient analyses. The need for large pressure gradients to produce from shale reservoirs through multifractured horizontal wells (MFHWs) may induce considerable changes in rock and fluid properties that can largely affect transient bottom-hole pressure response which can result in inaccurate predictions for well performance. Therefore, the assumption of constant properties in shale reservoirs may not be safe when modeling MFHW performance. This paper presents a nonlinear analytical MFHW performance model for single-phase systems based on the five-region model (Stalgorova and Mattar in SPE Reserv Eval Eng 16(03):246-256, 2013) that accounts for pressure-dependent rock and fluid properties in liquid-rich shales. Properties are assumed to vary exponentially with pressure. Because of this, the resulting nonlinear diffusivity equation is linearized by means of an exponential transformation. The nonlinear MFHW performance model is benchmarked against numerical simulation data for a number of case studies. The proposed analytical solution is able to accurately capture transient bottom-hole pressure response while delivering a highly accurate estimation of depletion time. In this study, it was found that nonlinear diffusion processes in liquid-rich shales, under the assumption of exponential changes in properties with pressure, are fully described by the porous medium equation (PME). The PME is presented along with a straightforward application to identify and forecast flow regimes in the reservoir (fast, normal or slow diffusion). Finally, a brief review on diagnostic plots for systems with pressure-dependent properties concludes this work. [ABSTRACT FROM AUTHOR]

The aim of this study is to combine numerical and experimental approaches to evaluate the influence of pleat geometrical parameters on the pressure drop and air velocity field at the vicinity of pleated fibrous filters. For a given filter, three different geometrical pleat configurations (with various pleat heights and widths) are investigated at similar filtration velocities. Numerical simulations are validated based on experimental measurements in terms of pressure drop versus filtration velocity, and enable the influence of the filter geometry on the air flow pattern in its vicinity to be investigated. The influence of filter geometry on the pressure drop is evaluated from experiments carried out in a lab-scale air handling unit. For this purpose, pleated filter prototypes were designed in the laboratory. [ABSTRACT FROM AUTHOR]

Surface dielectric barrier discharge (SDBD) is an important form of atmospheric discharge. The present study uses particle image velocimetry to investigate the influence of the duty cycle and pulse frequency on the flow field of plasma-induced jets and turbulent flow features for high-frequency high-voltage AC actuation under a low pressure of 7 kPa. The results prove that the SDBD plasma induces a suction flow and a horizontal tangential flow. Both the duty cycle and the pulse frequency have significant effects on the induced flow field. With the increasing duty cycle, the length and velocity of the jets increase linearly, the exit angle increases, and the Reynolds number of the tangential jet increases. The tangential jet transitions from turbulent to laminar flow as the duty cycle increases. As the pulse frequency increases, both the length of the tangential jet and the exit angle decrease gradually, and this trend accelerated near 30 Hz. The Reynolds number of the tangential jet increases to a maximum and then decreases with the increasing pulse frequency, with a peak near 50 Hz. The pulse frequency has little effect on the velocity of the jets or the turbulent flow characteristics of the tangential jet. A low duty cycle and a low pulse frequency should be adopted to increase the turbulent flow area and jet size to achieve a better actuation effect. [ABSTRACT FROM AUTHOR]

In this paper, a novel design of a rotary hydraulic flow control valve has been presented for high flow rate fluid power systems. High flow rates in these systems account for substantial flow forces acting on the throttling elements of the valves and cause the application of mechanically sophisticated multi-staged servo valves for flow regulation. The suggested design enables utilisation of single-stage valves in power hydraulics operating at high flow rates regimes. A spool driver and auxiliary mechanisms of the proposed valve design were discussed and selection criteria were suggested. Analytical expressions for metering characteristics as well as steady flow torques have been derived. Computational fluid dynamics (CFD) analysis of steady state flow regimes was conducted to evaluate the hydraulic behaviour of the proposed valve. This study represents a special case of an independent metering concept applied to the design of power hydraulic systems with direct proportional valve control operating at flow rates above 150 litres per minute. The result gained using parametric CFD simulations predicted the induced torque and the pressure drops due to a steady flow. Magnitudes of these values prove that by minimising the number of spool's mobile metering surfaces it is possible to reduce the flow-generated forces in the new generation of hydraulic valves proposed in this study. Calculation of the flow jet angles was analytically verified by measuring the deflection of the velocity vector using flow velocity field distribution, obtained during visualisation of the results of CFD simulations. The derived calculation formulas can predict metering characteristics, values of steady flow torques and jet angles for the specified design and geometry of the suggested valve. The proposed novel structure of the flow control valve promises to attain improved controllability, reliability and efficiency of the hydraulic control units of heavy mobile machinery operating at high flow rates regimes. [ABSTRACT FROM AUTHOR]

The compatibility of phases within the CaO-SiO2-Al2O3-SO3-Fe2O3 system is revisited. The influence of the SO2 partial pressure on the formation of phases and the stability of phase assemblages is addressed by means of new experimental methods (performed under controlled atmospheres) and thermodynamic calculations. Existing data from the literature are compiled and compared with the results obtained from this work. The results obtained are linked to real clinker formulations, and practical implications are discussed. [ABSTRACT FROM AUTHOR]

The initiation of combustion of lean H 2 :air mixtures, E R = 0.5 -- 0.6 , by nanosecond surface dielectric barrier discharge (nSDBD) was studied experimentally at high initial pressures, P = 3 -- 6 bar. The discharge was studied in different gas mixtures for the pressure range 1–12 bar. The ignition was initiated by two different discharge modes: streamer or filamentary nSDBD. The influence of the discharge structure and energy deposition on the ignition was demonstrated. Three regimes of multi-point ignition were observed: ignition with a few kernels, quasi-uniform ignition along the edge of the high voltage electrode and ignition along the plasma channels. The velocities of flame propagation were analyzed. The minimum ignition energy of the discharge and ignition delay time of combustion have been measured and analyzed with the help of kinetic numerical modeling. [ABSTRACT FROM AUTHOR]

High temperature (1 270-1 550 ºC) and high pressure (1.0 GPa) experimental studies on Re-bearing capabilities of pyrite, galena and sphalerite from typical Pb-Zn ore deposits were performed on a six-anvil apparatus. We observed microstructures of the quenched sulfides using scanning electron microscope (SEM) and analyzed compositions of the run products using both energy disperse spectroscopy (EDS) and electron probe microanalyzer (EPMA). The results show that pyrite melt can dissolve much more metallic Re than galena and sphalerite melts, forming scattered acicular ReS in the quenched matrix of pyrrhotite (FeS). The quenched matrixes of FeS, PbS and ZnS generally contain less than 1.0 wt.% of Re and their Re-bearing capabilities seem to range as FeS>PbS>ZnS. However, Re partition coefficients between them are difficult to estimate, because Re distribution is inhomogeneous in the quenched sulfide matrixes. [ABSTRACT FROM AUTHOR]

The light weight ceramics materials like silicon carbide, boron carbide and alumina have major application in vehicle armour and tank amours due to their low density and high compressive strength properties. The mechanical response of these ceramic materials has been investigated using explosive driven plate impact method. In present studies, hugoniot elastic limit (HEL) from pressure-time profile using manganin gauge and shock EOS in the pressure region 20 GPa to 100 GPaof boron carbide, silicon carbide and alumina were determined. In manganin gauge trace, the delayed failure observed also during shock loading. [ABSTRACT FROM AUTHOR]

Bars alignment in a Split Hopkinson Pressure Bar influences the quality of signal recorded during experiments, and thus affects the data of material properties being measured. There are some parameters directly related to the bars alignment such as their straightness, the impact face parallelism, and the neutral axis offset. This paper presents the study on the effects of non-straightness of an SHPB bar systems, dome shaped specimen, and striker bar to incident bar offset using numerical simulations. The bar component is made of AISI 4340 material with 10 mm diameter and 1000 mm length. The non-straightness of the bars and dome shaped specimen which occured due to the limitation of manufacturing process and availability of material, were measured by using dial gauges with ring supports in every 100 mm. First the simulation of an SHPB using ideal bar geometries were carried out. The simulations were then repeated by incorporating bar straightness, specimen surface, and striker bar to incident bar offset in the numerical model. From the comparisons of the material properties obtained from all simulations, it can be concluded that dome shaped specimen is the most affecting factor to the results of the SHPB measurement.. [ABSTRACT FROM AUTHOR]

In order to get further insight into the dynamic property of the vortex, pressure signals at various axial, radial and circumferential positions in a gas-solid cyclone were measured by multi-input dynamic pressure transducer. By adopting probability density function, standard deviation, and power spectral density methods, the characteristics of the pressure signals were analyzed and discussed. Experimental results show that there are two dominant frequencies (about 71 Hz and 179 Hz) of the pressure fluctuation in the gas flow: the former (about 71 Hz) is related to the quasi-forced vortex rotation; the latter (about 179 Hz) is related to the swing of the quasi-forced vortex core. The particle strands motion in the gas-solid flow reduces the dispersion of pressure fluctuation, mitigates the off-axis phenomenon of the core to some extent, and adds a dominant low frequency (0.31 Hz–0.86 Hz) which gets higher with the increase of inlet solids loading. The experimental results can provide insight into the pressure fluctuation in a gas-solid cyclone separator. [ABSTRACT FROM AUTHOR]

In turbulent fragmentation, star formation occurs in condensations created by converging flows. The condensations must be sufficiently massive, dense and cool to be gravitationally unstable, so that they start to contract; and they must then radiate away thermal energy fast enough for self-gravity to remain dominant, so that they continue to contract. For the metallicities and temperatures in local star-forming clouds, this second requirement is only met robustly when the gas couples thermally to the dust, because this delivers the capacity to radiate across the full bandwidth of the continuum, rather than just in a few discrete spectral lines. This translates into a threshold for vigorous star formation, which can be written as a minimum ram pressure PCRIT ~ 4 ⨰ 10-11 dyne. PCRIT is independent of temperature, and corresponds to flows with molecular hydrogen number density nH2.FLOW and velocity υFLOW satisfying nH2.FLOWυ2 FLOW≳800 cm-3 (km s-1)2. This in turn corresponds to a minimum molecular hydrogen column density for vigorous star formation, NH2.CRIT ~ 4 ⨰ 1021 cm-2 (∑CRIT ~ 100M☉ pc-2), and a minimum visual extinction AV, CRIT ~ 9 mag. The characteristic diameter and line density for a star-forming filament when this threshold is just exceeded - a sweet spot for local star formation regions - are 2RFIL ~ 0.1 pc and μFIL ~ 13M☉ pc-2. The characteristic diameter and mass for a prestellar core condensing out of such a filament are 2RCORE ~ 0.1 pc and MCORE ~ 1M☉. We also show that fragmentation of a shock-compressed layer is likely to commence while the convergent flows creating the layer are still ongoing, and we stress that, under this circumstance, the phenomenology and characteristic scales for fragmentation of the layer are fundamentally different from those derived traditionally for pre-existing layers. [ABSTRACT FROM AUTHOR]

We show that a resonant magnetic perturbation applied to the boundary of an ideal plasma screwpinch equilibrium with nested surfaces can penetrate inside the resonant surface and into the core. The response is significantly amplified with increasing plasma pressure. We present a rigorous verification of nonlinear equilibrium codes against linear theory, showing excellent agreement. [ABSTRACT FROM AUTHOR]

Highly coherent structures associated with an extremely long-lived saturated magnetohydrodynamic instability have been observed in KSTAR tokamak under a long-pulse and steady-state operation. They persist essentially unchanged for the full duration of a discharge up to 40 s, much longer than any dynamical or dissipative time scales in the system. Analysis of the data, supported by numerical simulations, indicates that they may be associated with a pressure-driven mode causing some degradation in the toroidal rotation, electron, and ion energy confinement. [ABSTRACT FROM AUTHOR]

Pressure swing adsorption of nitrogen onto granular activated carbon in the single-bed adsorber-desorber chamber has been studied at six different pressures 6-18 kgf/cm to evaluate their performance as an alternative refrigeration technique. Refrigerating effect showed a linear rise with an increase in the operating pressure. However, the heat of adsorption and COP exhibited initial rise with the increasing operating pressure but decreased later after reaching a maximum value. The COP initially increases with operating pressures however, with the further rise of operating pressure it steadily decreased. The highest average refrigeration, maximum heat of adsorption and optimum coefficient of performance was evaluated to be 415.38 W at 18 kgf/cm, 92756.35 J at 15 kgf/cm and 1.32 at 12 kgf/cm, respectively. The system successfully produced chilled water at 1.7 °C from ambient water at 28.2 °C. [ABSTRACT FROM AUTHOR]

The bed material and the fuel particles are the main actors in the agglomeration process in a bubbling fluidized bed reactor during a gasification conversion. The physical and chemical reactions between them determine whether the bed operates under a proper fluidization condition or the quality of the fluidization is deteriorated due to agglomerates appearance inside the bed. This work analyzes the pressure signals of a fluidized bed during Cynara cardunculus L. gasification in a reactor with an inner diameter of 52.8 mm. Jetsam and flotsam behavior of fuel particles is analyzed using sepiolite and silica sand as bed materials, respectively. The wide band energy and the attractor comparison tool are used to detect agglomeration, and, as a consequence, the defluidization of the bed. Similar defluidization times are obtained employing both methods. The wide band energy analysis shows that, for jetsam fuel particles, the endogenous bubbles produced by the fuel devolatilization inside the bed change the energy distribution, while for flotsam fuel particles, the cap-clinker agglomerate formed is detected by high frequencies in the power spectrum. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure laser ionization mass spectrometry (APLI-MS) is a powerful method for the analysis of polycyclic aromatic hydrocarbon (PAH) molecules, which are ionized in a selective and highly sensitive way via resonance-enhanced multiphoton ionization. APLI was presented in 2005 and has been hyphenated successfully to chromatographic separation techniques like high performance liquid chromatography (HPLC) and gas chromatography (GC). In order to expand the portfolio of chromatographic couplings to APLI, a new hyphenation setup of APLI and supercritical-fluid chromatography (SFC) was constructed and aim of this work. Here, we demonstrate the first hyphenation of SFC and APLI in a simple designed way with respect to different optimization steps to ensure a sensitive analysis. The new setup permits qualitative and quantitative determination of native and also more polar PAH molecules. As a result of the altered ambient characteristics within the source enclosure, the quantification of 1-hydroxypyrene (1-HP) in human urine is possible without prior derivatization. The limit of detection for 1-HP by SFC-APLI-TOF(MS) was found to be 0.5 μg L-1, which is lower than the 1-HP concentrations found in exposed persons. [ABSTRACT FROM AUTHOR]

A performance comparison is made between a Random Packed Bed (RPB) and a Packed Closed Cross Flow Structure (CCFS) reactor model for the Fischer–Tropsch Synthesis. The model incorporates an earlier reported reaction–diffusion catalyst model with chain growth probability depending on the local conditions. 180,000 full reactor simulations have been performed for an extensive parameter space exploration to determine optimal sets of parameters at the maximum Space Time Yield of C 5+ products. Results show that particles sizes tend to be minimized and the optimal inlet syngas ratio is relatively low (∼1). This study demonstrates the limitations of the RPB reactor at higher catalyst activities and shows the potential of the Packed CCFS reactor as an alternative. At catalyst activities of 3 times that reported by Yates–Satterfield the performance at optimal conditions of the Packed CCFS is 12% lower than RPB. At 10 times the YS activity the RPB takes relatively little advantage of the more active catalyst, productivity only increases by 24% compared to optimum conditions at 3 times YS activity. The Packed CCFS, on the other hand, is able to increase reactor productivity with 63% compared to its optimized benchmark conditions at 3 times YS activity. In spite of its lower catalyst inventory, the Packed CCFS can benefit from higher catalyst activities due to its improved heat transport properties and higher catalyst effectiveness at similar pressure drop over the reactor. Furthermore, larger reactor diameters can be applied with limited impact on the productivity per reactor volume. [ABSTRACT FROM AUTHOR]

We report comprehensive small angle neutron scattering measurements complemented by ac susceptibility data of the helical order, conical phase, and Skyrmion lattice phase (SLP) in MnSi under uniaxial pressures. For all crystallographic orientations uniaxial pressure favors the phase for which a spatial modulation of the magnetization is closest to the pressure axis. Uniaxial pressures as low as 1 kbar applied perpendicular to the magnetic field axis enhance the Skyrmion lattice phase substantially, whereas the Skyrmion lattice phase is suppressed for pressure parallel to the field. Taken together we present quantitative microscopic information on how strain couples to magnetic order in the chiral magnet MnSi. [ABSTRACT FROM AUTHOR]

The vapor pressure of PbBr 2 solid was measured by the Knudsen effusion method assuming that the vapor species consisted only of monomers. The vapor pressure of PbBr 2 fitted the following linear equation over the temperature range 532.3–633.9 K: ln ( p     ( Pa ) ) = − ( 16,653 ± 431 ) T     ( K ) + ( 26.47 ± 0.74 ) . The standard sublimation enthalpy of PbBr 2 was estimated to be 138.5 ± 3.6 kJ mol −1 , and the standard sublimation entropy was estimated to be 220.1 ± 6.2 J mol −1 K −1 . Identification of the predominant vapor species of PbBr 2 was conducted using mass spectrometry. From the analysis, the main vapor species of PbBr 2 solid is the PbBr 2 monomer. [ABSTRACT FROM AUTHOR]

An application of the standard test method for determining vapor pressure of pure compounds by thermal analyses (ASTM E 1782) was extended to vapor pressure measurements of narrow boiling range oil cuts by differential scanning calorimetry (DSC). The reliability of this application was examined by measuring comparable vapor pressure curves of selected narrow boiling oil cuts via a DSC based method and a static method. The oil cuts were distilled from a gasoline fraction (boiling range from about 363 to 453 K) from oil shale retorting oil, which was produced from Estonian kukersite oil shale by the Galoter process. The representative DSC measurements presented cover the temperature range from 318 to 484 K and pressure range from 15 to 750 kPa. Based on the results of the study, the DSC based method (ASTM E 1782) can be suggested as an alternative approach for determining vapor pressures of narrow boiling range oil cuts, with advantages such as a small sample size, use of commercial equipment and no need for sample degassing. [ABSTRACT FROM AUTHOR]

Taking into account the current social and economic environment, managers of social organizations are under a constant pressure to get results and to optimize costs with an efficient allocation of resources. Performance management allows measuring the results of public and private organizations which provide social care for the elderly. The potential of social services to respond to current challenges is linked not only to financial resources, but also to the ability of social managers to develop methods, techniques and innovative practices. Since innovation requires change, the providers should promote management practices and structures that favour the expression of new ideas. The article presents the results of a mixedtype research methodology based on qualitative and quantitative methods, such as the indepth semi-structured interview, focus-group, and questionnaire with public policymakers, as well as with private and public providers of social services for older people. Research was conducted during October -- November 2014 and the instruments were developed by the team members. The aim of the research has been to find out the importance of performance and performance measurement among public and private managers of social services for older people, and also from the perspective of policymakers. Conclusions reveal that the managers of social services for elderly should be aware that measurement alone is not sufficient, as long as the information obtained is not used in other decision-making processes like: strategic planning, quality management, budgeting activities, increased productivity. The findings have implications for practitioners, researchers and policymakers. [ABSTRACT FROM AUTHOR]

This paper presents a novel micro-gripper design with the dual functions of manipulation and force sensing. The device consists of two parallel plates, each mounted on torsion bars, which can be made to rotate towards or away from each other by use of a pneumatically- or hydraulically-actuated elastic membrane. The plates can be conveniently fabricated using photo-etching and the design allows for a range of ratios between actuation pressure and tip opening displacement and force. The elastic gripping tips can be designed to provide sufficient compliance that their strain can be used to monitor and control the gripping force. An exemplar device has been fabricated and its behaviour characterised by a series of mechanical measurements of force and displacement. These measurements have been rationalised using a simple analytical model, backed up with finite element analysis to emphasise the design variables and scalability. This exemplar device, with a maximum tip opening amplitude of 1 mm and maximum force output of 50 mN, has also been demonstrated to perform pick-and-place operations with 200 μm micro-beads. [ABSTRACT FROM AUTHOR]

In this paper, a horizontal magnetic fluid pressure difference sensor based on a compound magnetic core is presented. The sensor is packaged in a glass pipe, in which two permanent magnets are fixed on either side of the pipe to provide restoring force to the compound magnetic core. The movement of the compound magnetic core is sensed via sensing coils. Then the structure and principle of horizontal magnetic fluid pressure difference sensor are illustrated, along with experiments on the laboratory-scale prototype of the horizontal magnetic fluid pressure difference sensor. The results of the experiments show that there is a linear relationship between the input intensity of pressure and the output voltage in a particular range, which indicates the feasibility of the novel magnetic fluid pressure difference sensor. [ABSTRACT FROM AUTHOR]

The Taiwan Photon Source (TPS) is a 3 GeV third generation accelerator light source. The vacuum systems contain an electron storage ring (SR) of 518.4 m in circumference and a concentric booster (BR) of 496.8 m in circumference, linked with the transport lines one from the booster to storage ring (BTS) and the other from the linear accelerator to the booster (LTB). To ensure the highest stability of the electron beam in the storage ring, all the vacuum systems for the SR, BTS, and BR, have been baked to the ultrahigh vacuum (UHV). The aluminum vacuum chambers with the completely oil-free precise manufacturing process provide a lowest surface outgassing rate and lowest broadband impedance for accommodating the beam in stable. The combination of the triode ion pumps and the non-evaporable getter (NEG) pumps provides a superior pumping efficiency and the ultimate pressure < 5 nPa. The 24 arc-cell vacuum systems, each about 14 m in length, have been baked to the UHV and sealed in the laboratory prior to transport to the TPS tunnel for the installation. Other vacuum systems were installed and baked on site in parallel. After completing the installations, commissioning of TPS was started in August 2014. [ABSTRACT FROM AUTHOR]

The concept of low pressure (LP) vacuum outlet gas chromatography (GC) was introduced more than 50 years ago, but it was not until the 2000s that its theoretical applicability to fast analysis of GC-amenable chemicals was realized. In practice, LPGC is implemented by placing the outlet of a short, wide (typically 10–15 m, 0.53 mm inner diameter) analytical column under vacuum conditions, which speeds the separation by reducing viscosity of the carrier gas, thereby leading to a higher optimal flow rate for the most separation efficiency. To keep the inlet at normal operating pressures, the analytical column is commonly coupled to a short, narrow uncoated restriction capillary that also acts as a guard column. The faster separations in LPGC usually result in worse separation efficiency relative to conventional GC, but selective detection usually overcomes this drawback. Mass spectrometry (MS) provides highly selective and sensitive universal detection, and nearly all GC-MS instruments provide vacuum outlet conditions for implementation of LPGC-MS(/MS) without need for adaptations. In addition to higher sample throughput, LPGC provides other benefits, including lower detection limits, less chance of analyte degradation, reduced peak tailing, increased sample loadability, and more ruggedness without overly narrow peaks that would necessitate excessively fast data acquisition rates. This critical review summarizes recent developments in the application of LPGC with MS and other detectors in the analysis of pesticides, environmental contaminants, explosives, phytosterols, and other semi-volatile compounds. [ABSTRACT FROM AUTHOR]

The evolution of laws on the use of biocide products has led to important changes in the field of wood preservation leading to an increasing interest for non "biocidal treatments" like thermal or chemical modifications. While thermal modifications become more and more common on industrial scale, development of chemical modifications progresses slowly. One reason for the challenges encountered is probably the difficulty to use actual vacuum pressure plant to impregnate wood with solutions of reactive chemicals aimed to react with or within the wood. In this context, the presented research focuses on a new alternative called axial impregnation, derived from Boucherie process, for impregnation of treatable non durable hardwood species. This process consists of low-pressure impregnation of green wood logs through its lower extremity with treatment solution transiting via natural pathways of vessels. In order to evaluate the feasibility of the method, logs of different hardwood species were impregnated with a copper based preservative solution and the distribution of copper within the wood was determined. Results indicated that treatable wood species like beech, hornbeam and birch can be easily and homogeneously treated using axial impregnation method, while ash known for its weak impregnability remained untreated. [ABSTRACT FROM AUTHOR]

Pressureless sintering and the two pressure assisted sintering technologies - sintering + hot isostatic pressing (sinter-HIP) and field assisted sintering technology (FAST) were used to produce a fine grained WC-6 Co hardmetal. In order to compare the mechanical properties of the hardmetals, which result from different sintering technologies, the material strength was determined. In the present study the uniaxial three point bending test and the biaxial ball on three balls test were used as strength measuring methods. The results were described by the Weibull distribution function. Additionally, the paper will analytically compare the two tests by describing the relation of the strength of the samples to their effective volumes. Based on this procedure components having arbitrary shapes and volumes can be designed. [ABSTRACT FROM AUTHOR]

The solubility of light fullerenes (C 60 and C 70 ) in 1-hexanol was investigated in the range of pressures of 0.1–100 MPa and in the range of temperatures of 298.15–363.15 K. In all of the studied temperatures, solubility increases monotonously with increasing pressure. At ambient pressure, we have found that the temperature dependence of solubility in the binary system C 60 –1-hexanol is non-monotonic: the solubility diagram consists of two branches corresponding to the crystallization of different solid phases and one invariant point corresponding to the simultaneous saturation of both phases (monosolvated fullerene C 60 and non-solvated C 60 ). The composition of the solid crystallosolvate was determined by thermogravimetric analysis. The solubility diagram of the binary system C 70 –1-hexanol in the temperature range of 298.15–328.15 K at 0.1 MPa consists of only one branch corresponding to the crystallization of non-solvated C 70 . [ABSTRACT FROM AUTHOR]

Two different experimental approaches for the evaluation of a bridge deck's stationary aerodynamic forces are studied in this paper: both wind tunnel measurement of global force and pressure distribution are evaluated on deck sectional models. Advantages and drawbacks of these different approaches are discussed using the results obtained on a simple deck section, specifically chosen to compare the selected methods. Two-dimensional computational fluid dynamics (CFD) simulations have been performed to provide an insight into the differences of the aerodynamic forces measured with the two methods. Specifically, the effect of shear stresses, measurement discretization, and axial correlation of pressures are addressed. In CFD analysis, several turbulence models are tested and discussed using Reynolds-averaged Navier- Stokes (RANS) equations. [ABSTRACT FROM AUTHOR]

The objective of this study is to develop and analyze a nonlinear suspended energy harvester (NSEH) that can be mounted on a rotating wheel. The device comprises a permanent magnet as a mass in the kinetic system, two springs, and two coil sets. The mass vibrates along the transverse direction because of the variations in gravitational force. This research establishes nonlinear vibration equations based on the resonance frequency variation of the energy harvester; these equations are used for analyzing the power generation and vibration of the harvester. The kinetic behaviors can be determined according to the stiffness in the two directions of the two suspended springs. Electromagnetic damping is examined to estimate the power output and effect of the kinematic behaviors on NSEH. The power output of the NSEH with a 52 Ω resistor connected in series ranged from approximately 30 to 4200 μW at wheel speeds that ranged from nearly 200 to 900 rpm. [ABSTRACT FROM AUTHOR]

The availability of tools for safety evaluation of a pressure liner is a relevant issue in both structural and hydraulic engineering. A suitable design of a steel liner may involve a significant reduction in the investment cost of a hydropower plant and may also ensure its future integrity, avoiding prolonged stoppages in the operation stage. First, a review of the design methods for steel pressure liners is outlined and certain key aspects for the critical buckling load assessment are pointed out. Second, a numerical modeling and analysis procedure of a steel pressure liner is presented. The methodology is based on 3D nonlinear finite element modeling procedures, involving both liner constraining and the effect of stiffeners. In addition, both large displacements and a surrounding elastic medium are assumed in the model. Besides, some types of geometric imperfections such as weld-induced ones, initial gap, ovality, and wall-thickness loss due to corrosion are taken into account in this work. Finally, some conclusions are drawn regarding the role of imperfections in the calculated critical pressure of a steel liner. [ABSTRACT FROM AUTHOR]

The present paper deals with the study of the pressure corrections to the viscous potential flow analysis of Kelvin-Helmholtz instability with tangential electric field at the interface of two viscous fluids. Viscosity enters through normal stress balance in the viscous potential flow theory and tangential stresses for two fluids are not continuous at the interface. Here we have considered viscous pressure in the normal stress balance along with the irrotational pressure and it is assumed that the addition of this viscous pressure will resolve the discontinuity between the tangential stresses and the tangential velocities at the interface of two fluids. The viscous pressure is derived by mechanical energy balance equation and this pressure correction applied to compute the growth rate of electrohydrodynamic Kelvin-Helmholtz instability. A dispersion relation is obtained and stability criterion is given in the terms of critical value of relative velocity. It has been observed that the inclusion of irrotational shearing stresses have stabilizing effect on the stability of the system. [ABSTRACT FROM AUTHOR]

The structural properties, electronic band structure and Bader charge of Sb2Te3 under hydrostatic pressure were simulated using density functional theory in order to study isostructural phase transitions (IPT) in Sb2Te3. The theoretical results showed that the axial ratio c / a did not exhibit any anomaly below 6 GPa. The variations of bond lengths were discontinuous at 2.5 GPa, which suggested considerable changes in interatomic interactions and provided sound support to the IPT. The effective charges of Sb and Te atoms showed significant discontinuous variations at 2.5 GPa, which revealed a strong redistribution of the electronic charge density and considerably changed interactions among bonding atoms. Thus, the IPT is originated from the considerable variation in the electronic charge density. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The aim of the paper is to describe the current status of management for the decommissioning of combustible waste in KAERI. In Korea, two decommissioning projects have been carried out due to the retiring of nuclear research facilities, i.e., the Korean research reactors (KRR-1 & KRR-2) and a uranium conversion plant (UCP). The decommissioning of KRR-2 and the uranium conversion plant (UCP) at KAERI were completely finished by 2011, whereas the decommissioning of KRR-1 is currently underway. For the purpose of a volume reduction of the combustible waste generated from the decommissioning projects, incineration technology has been selected for the treatment of combustible waste. About 16.4 tons of combustible waste has been treating using Oxygen Enriched Incineration. The temperature; pressure of the major components; stack gas concentrations, i.e., SO x , NO x , CO, CO 2 and HCl; and residual oxygen were measured. The major parameters measured during normal operation were sustained at a stable status within criteria of the operation condition. Oxygen enriched air, 22 vol.% (dry basis) was used for stable incineration. The volume reduction ratio achieved was about 1/65. [ABSTRACT FROM AUTHOR]

The multihole pressure probes are widely used to determine flow velocity vectors and pressures in the fluid machinery fields due to their robustness, convenience, and economy in flow measurement. Accuracy and fast calibration of a multihole pressure probe is very important. In this article, a multihole pressure probe automatic calibration system is developed. The hardware device mainly consists of computer, motion control equipment and data acquisition ( DAQ) equipment, and the software program is developed using the G-language based on LabVIEW platform. The fundamental theory and method of multihole pressure probes is reviewed, as well as about how to take into account the compressibility effect of the fluid. The developed system can be easily integrated by engineers in research institutes or industries, without requiring more expertise in programming or multihole probe measurement method. Furthermore, the system is used for a five-hole probe's calibration and measurement, satisfactory results are obtained. 0.5° is the maximum uncertainty for the flow angles and 1.7% is for the velocity magnitude. The measurement biases being caused by the effect of Reynolds number are investigated. In the Reynolds number range of 1.06 × 104 to 4.29 × 104, the measurement biases of velocity vector are presented. [ABSTRACT FROM AUTHOR]

The objective of this paper is the further investigation of the shell intersection problem. The pad reinforced nozzle connections of the cylindrical vessel under internal and external loads are investigated using elastic-plastic analysis and the stress analysis in intersecting shells (SAIS) special-purpose computer program. The method for determining the plastic limit load based on the maximum criterion of the rate of the change of the relative plastic work and program module LOAD_PL for its realization are presented. The results of comparisons with the twice elastic-slope (TES) method were considered for determining the plastic limit load using known experimental data for models of a pad reinforced cylindrical vessel with a radial nozzle under a transverse force. The results of a parametric study of unreinforced and pad reinforced vessel models with a nozzle under internal pressure, in-plane moment, and out-plane moment loadings are discussed. [ABSTRACT FROM AUTHOR]

The steam turbine blades of low pressure stages are endangerd by the high-cyclic fatigue due to the combined loading of dynamic stresses by the steam time-variant pressure and the pre-stress from centrifugal forces. Therefore, the importance of their experimental dynamic analysis in the design stage is critical. For laboratory tests of the blades, the piezo actuators placed on the blades, unlike electromagnets placed in the stationary space, give a possibility to excite the flexural vibration of the blades within the bladed disk by time continuous forces independently of the rotor revolutions. In addition, the piezo actuators can be also used to control the vibrations of the blade. Therefore, several dynamic experiments of the clamped model blade equipped with PVDF films were performed for the force description of the piezo foils and their behavior as actuators of the blade vibration. The numerical beam models were used for numerical analysis of the vibration suppression effects both by additional parametric excitation and by active damping. The optimal phase shift of piezo actuator voltage supply was ascertained both for amplitude amplification and suppression. The results contribute to the knowledge of the actuation and active damping of blade vibration by the piezo elements [ABSTRACT FROM AUTHOR]

Square-planar d8-ML4 complexes might display subtle but noticeable local Lewis acidic sites in axial direction in the valence shell of the metal atom. These sites of local charge depletion provide the electronic prerequisites to establish weakly attractive 3c-2e M⋅⋅⋅HC agostic interactions, in contrast to earlier assumptions. Furthermore, we show that the use of the sign of the 1H NMR shifts as major criterion to classify M⋅⋅⋅HC interactions as attractive (agostic) or repulsive (anagostic) can be dubious. We therefore suggest a new characterization method to probe the response of these M⋅⋅⋅HC interactions under pressure by combined high pressure IR and diffraction studies. [ABSTRACT FROM AUTHOR]

Experimental studies of pressure fluctuation transducers with various types of protective grids against aerodynamic interactions are reported. The transient characteristics of the protective grids are estimated. The resolution of the different protective grids is studied and compared with calculated estimates. It is found that resonance phenomena can develop in the air cavity of the sensor with different types of grids. [ABSTRACT FROM AUTHOR]

By integrating the classical Boussinesq expression we derive analytically the vertical stress distribution induced by pressures distributed with arbitrary laws, up to the third order, over polygonal domains. Thus, one can evaluate in closed form either the vertical stress produced by shell elements, modelling raft foundations by finite elements, acting over a Winkler soil or those induced by a linear pressure distribution simulating axial force and biaxial bending moments over a pad foundation. To this end we include charts and tables, both for rectangular and circular domains, which allow the designer to evaluate the vertical stresses induced by linear load distributions by hand calculations. The effectiveness of the proposed approach is witnessed by the comparison between the analytical results obtained with the proposed formulas and the numerical ones of a FEM discretization of the soil associated with the loading distribution induced by a foundation modeled by plate elements resting on a Winkler soil. [ABSTRACT FROM AUTHOR]