Extra Shift Research Articles

Review of Hydrogen Production by Catalytic Aqueous‐Phase Reforming

AbstractCatalytic aqueous‐phase reforming (APR) produces higher quality hydrogen (with less carbon monoxide) and carbon dioxide from weak solutions of bio‐carbohydrates in a single reactor at low temperatures. It provides a good opportunity for the effective valorisation of biomass‐derived products. It is advantageous than steam reforming because it saves energy by avoiding vaporization of the biofeed and lowers cost by precluding an extra water gas shift reactor. As evident from the numerous published works during the past decade, there is growing academic and industrial interest in the APR process. This review updates recent literature on APR of many biomass surrogates such as glycerol, ethylene glycol, sorbitol, ethanol and glucose. Most works focused on the development of efficient catalysts for selective hydrogen production and they were deliberated comprehensively. Key insights into improved catalysts and reaction conditions were highlighted. New inferences on the thermodynamic, kinetic and reactor engineering aspects of the APR process were analysed too. This thorough appraisal of the current literature, which is hitherto missing, will surely contribute to the development of the next generation of catalysts and reactors for commercial applications of the APR process.

Analytical phase‐lead controller design using pole placement: a pole‐zero ratio minimisation approach

Owing to their simple structure and considerable improvement to the transient response, phase-lead controllers are broadly used in industrial applications. They are designed using root locus or Bode diagrams to introduce extra phase shift at the crossover frequency. Traditional phase-lead design techniques are either graphical or based on trial-and-error. In design techniques using root locus diagrams, there is no direct control on the values of a given time-domain performance index. To make this criterion satisfactory, the designer has to try different locations of the controller's zero and pole. Based on minimisation of the controller's pole-zero ratio subject to pole placement requirements, a simple analytical design technique is developed in this Letter. The necessary and sufficient conditions to determine optimal controller parameters are provided. To evaluate the performance of the proposed method, it is applied to a single integrating plant with time delay.

Comparative study on nitridation and oxidation plasma interface treatment for AlGaN/GaN MIS-HEMTs with AlN gate dielectric

This paper demonstrated the comparative study on interface engineering of AlN/AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) by using plasma interface pre-treatment in various ambient gases. The 15 nm AlN gate dielectric grown by plasma-enhanced atomic layer deposition significantly suppressed the gate leakage current by about two orders of magnitude and increased the peak field-effect mobility by more than 50%. NH3/N2 nitridation plasma treatment (NPT) was used to remove the 3 nm poor-quality interfacial oxide layer and N2O/N2 oxidation plasma treatment (OPT) to improve the quality of interfacial layer, both resulting in improved dielectric/barrier interface quality, positive threshold voltage (Vth) shift larger than 0.9 V, and negligible dispersion. In comparison, however, NPT led to further decrease in interface charges by 3.38 × 1012 cm−2 and an extra positive Vth shift of 1.3 V. Analysis with fat field-effect transistors showed that NPT resulted in better sub-threshold characteristics and transconductance linearity for MIS-HEMTs compared with OPT. The comparative study suggested that direct removing the poor interfacial oxide layer by nitridation plasma was superior to improving the quality of interfacial layer by oxidation plasma for the interface engineering of GaN-based MIS-HEMTs.

Trust makes Twitter plea for off-duty staff to help in A&E.

Emergency department pressures caused by an influx of patients to a hospital trust prompted a plea on social media and radio for off-duty nurses to work an extra shift.

Electronic structures of doped BaFe2As2 materials: virtual crystal approximation versus super-cell approach

Employing virtual crystal approximation and super-cell methods for doping, we have performed a comparative study of the electronic structures of various doped BaFe$_2$As$_2$ materials by first principles simulations. Both of these methods give rise to a similar density of states and band structures in case of hole doping (K doping in Ba site) and iso-electronic P doping in As site. But in case of electron doped systems with higher doping concentration, electronic structures, calculated using virtual crystal approximation approach deviates from that of the super-cell method. On the other hand in case of iso-electronic Ru doping implemented by virtual crystal approximation, an extra shift of the chemical potential in electronic structure in comparison to super-cell method is observed and that shift can be used to predict the correct electronic structure within virtual crystal approximation as reflected in our calculated Fermi surfaces. But for higher Ru doping concentration, simple shifting of chemical potential does not work as the electronic structure calculated by virtual crystal approximation approach is entirely different from that of the calculated by super-cell formalism.

Tunable Fano-like resonance enabled by coupling a microsphere with a fiber Mach-Zehnder interferometer.

We demonstrate a simple scheme to achieve Fano-like resonance by coupling a microsphere resonator with a fiber Mach-Zehnder interferometer (FMZI), which includes a tapered microfiber in one pathway to evanescently couple with the microsphere. In this system, Fano-like asymmetric lineshapes could be converted into different types by introducing an extra phase shift in the FMZI. In addition, the sharpness of the Fano-like lineshapes could be controlled by changing the coupling strength between the microsphere and the microfiber. This Fano-like resonance with advantages of fiber integration, tunable lineshape, and ease of operation may have great potential in optical signal processing and sensing.

Structural Metastability and Quantum Confinement in Zn1-xCoxO Nanoparticles.

This paper investigates the electronic structure of wurtzite (W) and rock-salt (RS) Zn1-xCoxO nanoparticles (NPs) by means of optical measurements under pressure (up to 25 GPa), X-ray absorption, and transmission electron microscopy. W-NPs were chemically synthesized at ambient conditions and RS-NPs were obtained by pressure-induced transformation of W-NPs. In contrast to the abrupt phase transition in W-Zn1-xCoxO as thin film or single crystal, occurring sharply at about 9 GPa, spectroscopic signatures of tetrahedral Co(2+) are observed in NPs from ambient pressure to about 17 GPa. Above this pressure, several changes in the absorption spectrum reveal a gradual and irreversible W-to-RS phase transition: (i) the fundamental band-to-band edge shifts to higher photon energies; (ii) the charge-transfer absorption band virtually disappears (or overlaps the fundamental edge); and (iii) the intensity of the crystal-field absorption peaks of Co(2+) around 2 eV decreases by an order of magnitude and shifts to 2.5 eV. After incomplete phase transition pressure cycles, the absorption edge of nontransformed W-NPs at ambient pressure exhibits a blue shift of 0.22 eV. This extra shift is interpreted in terms of quantum confinement effects. The observed gradual phase transition and metastability are related to the NP size distribution: the larger the NP, the lower the W-to-RS transition pressure.

Low-Phase-Noise 54-GHz Transformer-Coupled Quadrature VCO and 76-/90-GHz VCOs in 65-nm CMOS

This paper presents new circuit topologies and design techniques for low-phase-noise (PN) complementary metal–oxide–semiconductor (CMOS) millimeter-wave quadrature voltage-controlled oscillator (QVCO) and VCOs. A transformer-coupled QVCO topology with extra phase shift is proposed to replace the coupling transistors, which eliminates coupling transistors’ noise, decouples the tradeoff between PN and phase error, and improves the PN performance. This technique is demonstrated in a millimeter-wave QVCO with a measured PN of −119.2 dBc/Hz at 10-MHz offset of a 56.2-GHz carrier and a tuning range of 9.1%. In addition, an inductive-divider-feedback technique is proposed in an $LC$ VCO design to improve the transconductance linearity, resulting in a larger signal swing and lower PN compared with the conventional $LC$ VCOs. The effectiveness of this approach is demonstrated in a 76- and a 90-GHz VCO design, both fabricated in a 65-nm CMOS process, with an FOM $_{{\mathrm {T}}}$ of 173.6 and 173.1 dBc/Hz, respectively.

Optical Encryption of a Binary Image by Phase Modulation of the Wavefront

We present a new scheme for optical encryption of a binary image. In our method, the original binary data page is first divided into two identical pages. In each data page, the “on” and “off” pixels are represented by two discrete phases that are 90° apart. The first page corresponds to the phase conjugation of the second page, and vice versa. In addition, the wavefront of the two data pages is changed simultaneously from planar to spherical, for better encryption. The wavefront modification is represented by an extra phase shift, which is a function of position on the wavefront. In this way the two separate pages are both encrypted, and therefore the pages cannot be distinguished in a CCD. If the first page is used as an encrypted data page, then the second page is used as the decryption key, and vice versa. The decryption can be done by simply combining the two encrypted data pages. It is shown in our experiment that encryption and decryption can be fully accomplished in the optical domain.

The Mössbauer rotor experiment and the general theory of relativity

In the recent paper Yarman et al. (2015), the authors claim that our general relativistic analysis in Corda (2015), with the additional effect due to clock synchronization, cannot explain the extra energy shift in the Mössbauer rotor experiment. In their opinion, the extra energy shift due to the clock synchronization is of order 10−13 and cannot be detected by the detectors of γ-quanta which are completely insensitive to such a very low order of energy shifts. In addition, they claim to have shown that the extra energy shift can be explained in the framework of the so-called YARK gravitational theory. They indeed claim that such a theory should replace the general theory of relativity (GTR) as the correct theory of gravity.In this paper we show that the authors Yarman et al. (2015) had a misunderstanding of our theoretical analysis in Corda (2015). In fact, in that paper we have shown that electromagnetic radiation launched by the central source of the apparatus is redshifted of a quantity 0.6̄v2c2 when arriving to the detector of γ-quanta. This holds independently by the issue that the original photons are detected by the resonant absorber which, in turns, triggers the γ-quanta which arrive to the final detector. In other words, the result in Corda (2015) was a purely theoretical result that is completely independent of the way the experiment is concretely realized. Now, we show that, with some clarification, the results of Corda (2015) hold also when one considers the various steps of the concrete detection. In that case, the resonant absorber detects the energy shift and the separated detector of γ-quanta merely measures the resulting intensity.In addition, we also show that the YARK gravitational theory is in macroscopic contrast with geodesic motion and, in turn, with the weak equivalence principle (WEP). This is in contrast with another claim of the authors of Yarman et al. (2015), i.e. that the YARK gravitational theory arises from the WEP. Therefore, the YARK gravitational theory must be ultimately rejected. We also correct the confusion of the authors of Yarman et al. (2015) concerning their claims about the possibility to localize the gravitational energy and, in turn, to define a stress–energy tensor for the gravitational field. In fact, we show that these claims are still in macroscopic contrast with the WEP.

Comparisons between Full-time and Part-time Pediatric Emergency Physicians in Pediatric Emergency Department

Pediatric emergency medicine is a young field that has established itself in recent decades. Many unanswered questions remain regarding how to deliver better pediatric emergency care. The implementation of full-time pediatric emergency physicians is a quality improvement strategy for child care in Taiwan. The aim of this study is to evaluate the quality of care under different physician coverage models in the pediatric emergency department (ED). The medical records of 132,398 patients visiting the pediatric ED of a tertiary care university hospital during January 2004 to December 2006 were retrospectively reviewed. Full-time pediatric emergency physicians are the group specializing in the pediatric emergency medicine, and they only work in the pediatric ED. Part-time pediatricians specializing in other subspecialties also can work an extra shift in the pediatric ED, with the majority working in their inpatient and outpatient services. We compared quality performance indicators, including: mortality rate, the 72-hour return visit rate, length of stay, admission rate, and the rate of being kept for observation between full-time and part-time pediatric emergency physicians. An average of 3678±125 [mean±standard error (SE)] visits per month (with a range of 2487-6646) were observed. The trends in quality of care, observed monthly, indicated that the 72-hour return rate was 2-6% and length of stay in the ED decreased from 11.5hours to 3.2hours over the study period. The annual mortality rate within 48hours of admission to the ED increased from 0.04% to 0.05% and then decreased to 0.02%, and the overall mortality rate dropped from 0.13% to 0.07%. Multivariate analyses indicated that there was no change in the 72-hour return visit rate for full-time pediatric emergency physicians; they were more likely to admit and keep patients for observation [odds ratio=1.43 and odds ratio=1.71, respectively], and these results were similar to those of senior physicians. Full-time pediatric emergency physicians in the pediatric ED decreased the mortality rate and length of stay in the ED, but had no change in the 72-hour return visit rate. This pilot study shows that the quality of care in pediatric ED after the implementation of full-time pediatric emergency physicians needs further evaluation.

Mössbauer experiments in a rotating system: Recent errors and novel interpretation

We consider the energy shift between emission and absorption lines in the Mossbauer experiments in a rotating system in the view of a recently reported extra component of such a shift, in addition to the usual relativistic time dilation effect, expressed by the inequality k > 0.5 in the expression for the relative energy shift ΔE/E = −ku2/c2 (u is the orbital velocity, and c the light velocity in vacuum). We consider the recent attempts of re-interpretation of the Mossbauer rotor experiments, showing their incorrectness, and analyze the proposed explanations of the physical origin of this extra energy shift. This way we stress that the energy of nuclei located in crystal cells should be determined via relativistic quantum mechanics, involving the geometry of a rotating disc. We show that the standard theory yields k = 1/2; applying the YARK gravitational theory, we obtain k = 2/3 in a perfect agreement with experimental data.

PRESSURE SHIFT AND GRAVITATIONAL REDSHIFT OF BALMER LINES IN WHITE DWARFS: REDISCUSSION

The Stark-induced shift and asymmetry, the so-called pressure shift (PS) of $H_\alpha$ and $H_\beta$ Balmer lines in spectra of DA white dwarfs (WDs), as masking effects in measurements of the gravitational red shift in WDs, have been examined in detail. The results are compared with our earlier ones from before a quarter of a century (Grabowski et al. 1987, hereafter ApJ'87; Madej and Grabowski 1990). In these earlier papers, as a dominant constituent of the Balmer-line-profiles, the standard, symmetrical Stark line profiles, shifted as the whole by PS-effect, were applied to all spectrally active layers of the WD atmosphere. At present, in each of the WD layers, the Stark-line-profiles (especially of $H_\beta$) are immanently asymmetrical and shifted due to the effects of strong inhomogeneity of the perturbing fields in plasma. To calculate the Stark line-profiles in successive layers of the WD atmosphere we used the modified Full Computer Simulation Method (mFCSM), able to take adequately into account the complexity of local elementary quantum processes in plasma. In the case of the $H_\alpha$ line, the present value of Stark-induced shift of the synthetic $H_\alpha$ line-profile is about twice smaller than the previous one (ApJ'87) and it is negligible in comparison with the gravitational red shift. In the case of the $H_\beta$ line, the present value of Stark-induced shift of the synthetic $H_\beta$ line-profile is about twice larger than the previous one. The source of this extra shift is the asymmetry of $H_\beta$ peaks.

Raman Enhancement Caused by Gold Nanoparticles Clustered Between Graphene and Substrate.

Graphene, one of the most robust two-dimensional (2D) materials, has shown amazing electrical, optical and thermal properties. The contact of graphene to other materials leads to Raman enhancement or fluorescence variation in some cases. Here, we present one flexible substrate structure of graphene/clustered-gold-nanoparticles (CGNs)/PDMS to demonstrate the Enhanced Surface Raman Spectroscopy. The fluorescence quenching on graphene is explained as ground-state charge transfer. In addition, graphene is found to possess the ability of fluorescence quenching or Raman enhancement when there are CGNs underneath. Moreover, graphene can be used as a passivation layer, protecting the CGNs underneath from chemical bonding with other materials. The experimental results also confirm that the total extra Raman enhancement is attributed to the extra electron shift to graphene and the extra ground state charge transfer introduced by the CGNs. This artificially engineered structures based on 2D materials could yield characteristics that go far beyond those conventional materials, and such materials should lead to higher sophistication of optical manipulation.

In Depth Study of Ge Impact on Advanced SiGe PMOS Transistors

SiGe material brings outstanding advantages for pMOS transistors [1,2]. Low Vt values are much easier to control thanks to specific band structure. The strain induced by engineering of lattice mismatch with silicon leads to enhanced mobility and performances. However a lot remains to understand in these processes and performances. This paper puts the light on two effects: (1) an unexpected Vt shift induced by Ge and (2) the relative impact of Ge, strain and defects on the mobility gain.Many SiGe processes and architectures have been studied to allow clear and reproducible conclusions: (1) pMOS with a given Ge content and various stack thicknesses; (2) pMOS with a given stack and various Ge compositions; (3) SiGe pMOS performed by epitaxy or by Ge-enrichment technique, from unstrained or strained Si substrate, leading to various combinations of stress and Ge content. Both bulk and SOI devices have been processed. Data have been analyzed in a global and coherent view, thus avoiding addressing non pertinent data. Extra Ge-induced Vfb shift: Advanced simulations have been performed using UTOX simulator [3,4]. 6×6 kp simulations and Poisson Schrodinger allow to simulate band structures with strain effects for all %Ge as well as electrical C(V) responses. Comparison between simulations and experiments indicates an extra Vt shift which is not expected from the band structure (Fig.1). This shift is proportional to %Ge content in the channel; it has been observed on SOI and Bulk devices.The analysis of the various gate stack thicknesses rules out an effect of charges in the stacks or at the interfaces. All the electrical data lead to a behavior explained with a Ge induced dipole at the SiGe/SiON interface. Detailed SIMS analysis (Fig.2) as well as STEM, EELS, HAADF experiments show a slight Ge diffusion in SiON probably explaining the dipole at this interface. Notice that this diffusion does not reach the SiON/HfO2 interface and the other existing dipole at this interface [5]. This result is essential for future devices design and modeling, as the extra shift is in the range of the expected Vt (~0.2V). Mobility on strained pMOS: The described processes induce an initial biaxial compressive stress in SiGe layer. This stress improves significantly the channel hole mobility. Meanwhile Ge atoms degrade the SiGe/SiON interface and increase the interface states density Dit (Fig.3). These Dit are related to Ge diffusion in SiON and induce dipoles. However they have no direct effect on Vt.Using the various technological splits available we have compared splits with similar final strain but different concentrations of Ge (Fig.4). This shows that the strain generated by lattice mismatch has a 1storder effect. The percentage of Ge itself as well as generated dipoles and Dit play a minor role, at least at the low %Ge (≤30%). At higher %Ge this is no more true and the gain by strain is counter-balanced by the interface degradation. An improvement of process is required to maintain a good interface quality.Real devices have 10-20 nm length and width. In this case the strain can relaxed depending on directions and may significantly increase or decrease the performances. A careful strain engineering is then expected. This will be discussed in the final paper.

Manifestation of Gouy phase anomaly in a coaxial focus array generated by a Dammann zone plate.

Gouy phase anomaly of the coaxial focus array generated by a Dammann zone plate (DZP) was investigated. Based on Debye vectorial diffraction theory, the longitudinal-differential (LD) phase profile was presented in the focal region of a high numerical aperture aplanatic objective with a DZP located before as the pupil filter. The numerical simulations show that there is a Gouy phase shift exactly located at the position of every diffraction order along the axial direction. Besides the well-known Gouy phase, a type of extra irregular phase shift among some diffraction orders is demonstrated. This interesting phenomenon of the extra phase shift, physically, is attributed to transversal confinement inside the pupil aperture of the focusing system, which is induced by the discontinuities in phase retardation between any two adjacent zones of DZPs. These extra irregular phase shifts are very different for different kinds of DZPs, and thus this extra phase shift effect can be seen as a characteristic of certain DZPs. In addition, the 3D differential phase maps are presented for investigation of the subtle phase evolution in the off-axis volume.

Total dissolved solids estimation with a fiber optic sensor of surface plasmon resonance

In this paper, surface plasmon spectra of ion influence was investigated by using a fabricated fiber optic sensors, then spectrum subtraction of ion and non-ionic solutions were developed for field applications of total dissolved solids (TDS) estimation. We confirmed the SPR spectral difference between seven ionic and three non-ionic liquid samples, that for the same refractive index, resonance wavelength in SPR spectrum is much higher for ionic samples than that in the case of non-ionic ones due to the ions influence. The positive correlation of ion content and extra resonance wavelength shift has been established for TDS estimation in water. With three groups of water samples investigation and field testing, the proposed SPR technique showed a good performance comparable to the conductivity method.

Coil response inversion for very early time modelling of helicopter‐borne time‐domain electromagnetic data and mapping of near‐surface geological layers

ABSTRACTVery early times in the order of 2–3 μs from the end of the turn‐off ramp for time‐domain electromagnetic systems are crucial for obtaining a detailed resolution of the near‐surface geology in the depth interval 0–20 m. For transient electromagnetic systems working in the off time, an electric current is abruptly turned off in a large transmitter loop causing a secondary electromagnetic field to be generated by the eddy currents induced in the ground. Often, however, there is still a residual primary field generated by remaining slowly decaying currents in the transmitter loop. The decay disturbs or biases the earth response data at the very early times. These biased data must be culled, or some specific processing must be applied in order to compensate or remove the residual primary field. As the bias response can be attributed to decaying currents with its time constantly controlled by the geometry of the transmitter loop, we denote it the ‘Coil Response’. The modelling of a helicopter‐borne time‐domain system by an equivalent electronic circuit shows that the time decay of the coil response remains identical whatever the position of the receiver loop, which is confirmed by field measurements. The modelling also shows that the coil response has a theoretical zero location and positioning the receiver coil at the zero location eliminates the coil response completely. However, spatial variations of the coil response around the zero location are not insignificant and even a few cm deformation of the carrier frame will introduce a small coil response. Here we present an approach for subtracting the coil response from the data by measuring it at high altitudes and then including an extra shift factor into the inversion scheme. The scheme is successfully applied to data from the SkyTEM system and enables the use of very early time gates, as early as 2–3 μs from the end of the ramp, or 5–6 μs from the beginning of the ramp. Applied to a large‐scale airborne electromagnetic survey, the coil response compensation provides airborne electromagnetic methods with a hitherto unseen good resolution of shallow geological layers in the depth interval 0–20 m. This is proved by comparing results from the airborne electromagnetic survey to more than 100 km of Electrical Resistivity Tomography measured with 5 m electrode spacing.

Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy

Though generally agreed that the symmetry energy plays a dramatic role in determining the structure of neutron stars and the evolution of core-collapsing supernovae, little is known in what concerns its value away from normal nuclear matter density and, even more important, the correct definition of this quantity in the case of unhomogeneous matter. Indeed, nuclear matter traditionally addressed by mean-field models is uniform while clusters are known to exist in the dilute baryonic matter which constitutes the main component of compact objects outer shells. In the present work we investigate the meaning of symmetry energy in the case of clusterized systems and the sensitivity of the proto-neutron star composition and equation of state to the effective interaction. To this aim an improved Nuclear Statistical Equilibrium (NSE) model is developed, where the same effective interaction is consistently used to determine the clusters and unbound particles energy functionals in the self-consistent mean-field approximation. In the same framework, in-medium modifications to the cluster energies due to the presence of the nuclear gas are evaluated. We show that the excluded volume effect does not exhaust the in-medium effects and an extra isospin and density dependent energy shift has to be considered to consistently determine the composition of subsaturation stellar matter. The symmetry energy of diluted matter is seen to depend on the isovector properties of the effective interaction, but its behavior with density and its quantitative value are strongly modified by clusterization.

Observation and measurement of an extra phase shift created by optically detuned light storage in metastable helium

Electromagnetically induced transparency (EIT) in metastable helium at room temperature is experimentally shown to exhibit light storage capabilities for intermediate values of the detuning between the coupling and probe beams and the center of the atomic Doppler profiles. An additional phase shift is shown to be imposed to the retrieved pulse of light when the EIT protocol is performed at non-zero optical detunings. The value of this phase shift is measured for different optical detunings between 0 and 2 GHz, and its origin is discussed.