Intrinsic Zero Research Articles

A TL study of protective glasses of mobile phones for retrospective dosimetry

Several studies have shown that certain components of mobile phones, such as electronic components, display or touch screen glass, are suitable as emergency dosimeters in case of radiological incidents. However, so far the methods are frequently destructive and in case of a dose assessment the mobile phone will be destroyed. In order to overcome this problem, alternative materials need to be sought and further research is necessary. Building on results of a previous study, we further investigated protective glasses in this work, which have become an alternative material for dose reconstruction. Protective glasses are easy to sample and cheap, have become very popular to protect the surface of phones, can be easily replaced without complete destruction of an expensive smartphone, thus a dose assessment method based on this material will potentially find much greater public acceptance. The aim of this study was to optimize the detection window by systematically investigating the radiation-induced TL signals and intrinsic zero dose signals. Using two selected detection windows, the long-term and optical stability of the TL signals were investigated. The set of nine different protective glass samples studied fell into two groups with different fading and optical bleaching characteristics. Further research is necessary in order to reduce the zero dose signal, to reinvestigate the dosimetric properties and to verify the final protocol using a realistic irradiation test.

ДВУХСТОРОННИЙ МЕТОД ОПРЕДЕЛЕНИЯ МЕСТА ОДНОФАЗНОГО ЗАМЫКАНИЯ НА ЗЕМЛЮ В СЕТЯХ С ИЗОЛИРОВАННОЙ НЕЙТРАЛЬЮ

Relevance Currently, on the part of enterprises operating 6–35 kV distribution networks, there is a request for a deep modernization of networks and the transformation of existing, outdated networks into digital ones. A separate aspect of modernization is the introduction of high-precision measuring devices and new principles of data transmission. At the same time, the probability of damage for various reasons remains. Single-phase earth faults in networks with isolated neutral are still the most common problem in distribution networks that do not have universal solutions. The problem is particularly acute with determining the location of single-phase earth faults. The opportunities provided by the introduction of digital networks can become the basis for the implementation of new algorithms for relay protection and determining the location of damage. Aim of research The article considers, developed by the authors, a two-way method for determining the location of damage in single-phase earth faults according to the parameters of the emergency mode when installing current transformers in all three phases. The two-way method of determining the location of damage is based on the use of zero-sequence currents and voltages, which are determined by calculation for phase current and voltage differences at the beginning and end of the line. The algorithm is focused on digital electrical networks equipped with high-precision measuring transformers and a communication channel. To calculate the parameters of the zero sequence, the differences of the phase emergency parameters at the beginning and at the end of the line are used. Research methods To develop and study a two-way method for determining the location of damage in single-phase earth faults, the principle of superposition in combination with the method of symmetrical components was used. Decomposition of three-phase currents and voltages into symmetrical components is a linear procedure. Therefore, the zero-sequence current in a three-phase line, in accordance with the superposition principle, can be represented as the sum of three zero-sequence currents, each of which is determined by one of the phase currents at zero values of phase currents in the other two phases. This application of the method of symmetric components is valid only for purely emergency values of phase currents. Therefore, in advance, the load current must be excluded from the phase currents of the emergency mode. Results It is shown that the use of the method of symmetric components for single-phase earth faults separately for the damaged phase and undamaged phases makes it possible to determine the zero-sequence current at the site of damage and the intrinsic zero sequence current of the damaged line. It is shown that this separation of the zero-sequence current makes it possible to distinguish two components of the zero sequence in the voltage difference at the ends of the line. Based on the allocation of two components in the current and voltage of the zero sequence, an algorithm for two-way determination of the damage location has been developed, which allows determining the distance to a single-phase earth fault in networks with an isolated neutral. To study the two-way method of determining the location of damage, a network model and a device for determining the location of damage were implemented in the MATLAB Simulink software package. A functional diagram of a two - way damage location detection device is presented. The performed studies on the model of the electrical network have shown the high accuracy of the proposed algorithm for determining the location of damage.

Influence of Dynamic Resistance on Current Distribution of HTS DC Cable Conductor for Feeder Lines and Large Scale Magnet

HTS DC cable conductors are promising because of high current density and intrinsic zero resistance. Therefore, HTS cable conductor with large current carrying capacity are expected to have widespread application in feeder lines and large scale magnets. At present, the conventional design of HTS cable conductor, general several of 10 kA, are designed with goal of uniform current distribution by adjusting winding pitch same as AC HTS cable since the ripple current is unavoidable in DC transmission line and AC current in process of exciting and demagnetizing is also alternative. Thus, AC magnetic field component generated on tapes of HTS cable conductor is non-negligible. If the AC magnetic field component is higher than the penetration field of the HTS tapes, there is inevitable dynamic resistance among them. Dynamic resistance is seldom considered in previously conventional design of DC cable conductors. The dynamic resistance significantly affects the current distribution among HTS tapes except for generating extra loss and incurring instability. Based on the conventional design method of uniform current, this paper presents the DC current distribution among layers by considering dynamic resistance, which is particularly much more significant for large current capacity HTS DC cable conductors with ripple currents.

Research progress of puckered honeycomb monolayers

Graphene, as the representative of two-dimensional materials, has varous novel physical properties and potential applications. The intrinsic zero band gap of graphene limits its application in semiconductor devices, and thus the search for new semiconducting alternative materials has become a current research hotspot. Phosphorene is the monolayer of black phosphorus and has a puckered honeycomb structure. Its advanced properties, such as adjustable direct band gap, high carrier mobility and in-plane anisotropy and so on, have recently aroused great research interest, thus opening up the research field of puckered honeycomb monolayers in group V elements. In this article, we first focus on the structure, synthesis and physical properties of five single-element two-dimensional materials (nitrogen, phosphorus, arsenic, antimony and bismuth) each with puckered honeycomb structure. Second, some binary two-dimensional materials with puckered honeycomb structure are discussed, including IV-VI and V-V compounds. These materials have their own unique crystal symmetry, and the properties can be controlled by changing their structures and dimensions. Finally, we also make a summary on some current challenges that need to be solved, and the possible future applications of these two-dimensional materials are also presented.

INTRINSIC SMALLNESS

AbstractRecent work in computability theory has focused on various notions of asymptotic computability, which capture the idea of a set being “almost computable.” One potentially upsetting result is that all four notions of asymptotic computability admit “almost computable” sets in every Turing degree via coding tricks, contradicting the notion that “almost computable” sets should be computationally close to the computable sets. In response, Astor introduced the notion of intrinsic density: a set has defined intrinsic density if its image under any computable permutation has the same asymptotic density. Furthermore, introduced various notions of intrinsic computation in which the standard coding tricks cannot be used to embed intrinsically computable sets in every Turing degree. Our goal is to study the sets which are intrinsically small, i.e. those that have intrinsic density zero. We begin by studying which computable functions preserve intrinsic smallness. We also show that intrinsic smallness and hyperimmunity are computationally independent notions of smallness, i.e. any hyperimmune degree contains a Turing-equivalent hyperimmune set which is “as large as possible” and therefore not intrinsically small. Our discussion concludes by relativizing the notion of intrinsic smallness and discussing intrinsic computability as it relates to our study of intrinsic smallness.

Pristine graphene: functionalization, fabrication, and nanocomposite materials

Graphene has a wide range of unique properties including high carrier mobility, optical transparency, and exceptional electrical and thermal conductivity. The interest in graphene has been largely fueled by its potential to revolutionize a number of technologically important areas including materials science, biomedical science, and energy. Despite its high potentials, major challenges still remain. These include poor solubility, intrinsic zero band gap energy, low reactivity and the availability of well-defined pristine graphene in large quantity, which have hampered the rapid development of graphene-based functional devices. Many of these challenges can be potentially addressed through chemical functionalization of the material. Covalent functionalization can enhance graphene’s properties including opening its band gap, tuning conductivity, improving solubility, and enhancing the properties of graphene-based composite materials. This paper discusses our work on the chemical functionalization of pristine graphene, and synthesis of graphene-nanoparticle composite materials and three-dimensional graphene (3DG)-TiO2 nanocomposite photocatalyst. In photocatalytic CO2 reduction, the 3DG-TiO2 nanocomposite demonstrated excellent activity, about 11 times higher than TiO2 nanoparticles.

Kinetics of Photocatalyzed Reactions: Five Lessons Learned.

Elucidation of kinetics of photocatalyzed chemical mechanisms occurring at interfaces (gas-solid, liquid-solid) has been challenging. We summarize here five lessons learned over five decades.1. An assumed reaction network leads to a single kinetic model, but a common model, the Langmuir–Hinshelwood rate equation, r = kcat K C/ [1 +KC], arises from multiple mechanisms, hence models alone do not reveal unique mechanisms.2. The Langmuir–Hinshelwood model parameter kcat represents the slow step at a catalyst surface, and in thermal catalysis, depends upon the reactant structure. However, early photocatalysis work with light chlorinated hydrocarbons in aqueous solutions showed a single kcat value, independent of reactant structure.3. The dependence of the Langmuir-Hinshelwood parameters, kcat and K, upon intensity indicates that a pseudo-steady state approach is more fundamental than the presumed equilibrated adsorption of the LH model.4. Dyes and phenols are commonly studied, and claimed as first order reactions, despite often exhibiting rate constants which diminish with increasing contaminant concentration. We show that such studies are the result of intrinsic zero order data plotted on a semilog graph, and involve zero order rate limitation by reactant saturation, electron transfer to O2, oxygen mass transfer, or light supply.5. The apparent kinetics for contaminant removal from photocatalytic self-cleaning surfaces depends upon multiple circumstances, including the geometry of reactant deposit, catalyst porosity, and reactant light absorption. A single decision table suffices to indicate the apparent reaction order, n, to assume when fitting photocatalytic kinetic data from self-cleaning surfaces to a power law rate form, rate = k Cn.

Near-Horizon Geodesics for Astrophysical and Idealised Black Holes: Coordinate Velocity and Coordinate Acceleration

Geodesics (by definition) have an intrinsic 4-acceleration zero. However, when expressed in terms of coordinates, the coordinate acceleration d 2 x i / d t 2 can very easily be non-zero, and the coordinate velocity d x i / d t can behave unexpectedly. The situation becomes extremely delicate in the near-horizon limit—for both astrophysical and idealised black holes—where an inappropriate choice of coordinates can quite easily lead to significant confusion. We shall carefully explore the relative merits of horizon-penetrating versus horizon-non-penetrating coordinates, arguing that in the near-horizon limit the coordinate acceleration d 2 x i / d t 2 is best interpreted in terms of horizon-penetrating coordinates.

Calibration of a rotating accelerometer gravity gradiometer using centrifugal gradients.

The purpose of this study is to calibrate scale factors and equivalent zero biases of a rotating accelerometer gravity gradiometer (RAGG). We calibrate scale factors by determining the relationship between the centrifugal gradient excitation and RAGG response. Compared with calibration by changing the gravitational gradient excitation, this method does not need test masses and is easier to implement. The equivalent zero biases are superpositions of self-gradients and the intrinsic zero biases of the RAGG. A self-gradient is the gravitational gradient produced by surrounding masses, and it correlates well with the RAGG attitude angle. We propose a self-gradient model that includes self-gradients and the intrinsic zero biases of the RAGG. The self-gradient model is a function of the RAGG attitude, and it includes parameters related to surrounding masses. The calibration of equivalent zero biases determines the parameters of the self-gradient model. We provide detailed procedures and mathematical formulations for calibrating scale factors and parameters in the self-gradient model. A RAGG physical simulation system substitutes for the actual RAGG in the calibration and validation experiments. Four point masses simulate four types of surrounding masses producing self-gradients. Validation experiments show that the self-gradients predicted by the self-gradient model are consistent with those from the outputs of the RAGG physical simulation system, suggesting that the presented calibration method is valid.

The LPF with improved stopband response designed for wideband microwave detectors

To achieve an improved stopband response including expanded stopband width, increased rejection level, and a smooth S11 phase response, a lowpass filter (LPF) is proposed based on the suspended microstrip line with naturally high characteristic impedance and the radial stub with intrinsic transmission zero. The usually unmentioned phase response, are critical to obtaining a wide and flat operating band for the microwave detector, since a smooth phase response exerts small load effects to the diode. As a demonstration, a detector employing the LPF is fabricated and measured. The measured results show that a wide operating band from 1.8 to 13.5 GHz with flat detection outputs of ripple less than 1 dB is obtained for the detector, which coincides with the smooth-phase range of the LPF.

Zero-group-velocity acoustic waveguides for high-frequency resonators

The propagation of the Lamb-like modes along a silicon-on-insulator (SOI)/AlN thin supported structure was simulated in order to exploit the intrinsic zero group velocity (ZGV) features to design electroacoustic resonators that do not require metal strip gratings or suspended edges to confine the acoustic energy. The ZGV resonant conditions in the SOI/AlN composite plate, i.e. the frequencies where the mode group velocity vanishes while the phase velocity remains finite, were investigated in the frequency range from few hundreds of MHz up to 1900 MHz. Some ZGV points were found that show up mostly in low-order modes. The thermal behaviour of these points was studied in the −30 to 220 °C temperature range and the temperature coefficients of the ZGV resonant frequencies (TCF) were estimated. The behaviour of the ZGV resonators operating as gas sensors was studied under the hypothesis that the surface of the device is covered with a thin polyisobutylene (PIB) film able to selectively adsorb dichloromethane (CH2Cl2), trichloromethane (CHCl3), carbontetrachloride (CCl4), tetrachloroethylene (C2Cl4), and trichloroethylene (C2HCl3), at atmospheric pressure and room temperature. The sensor sensitivity to gas concentration in air was simulated for the first four ZGV points of the inhomogeneous plate. The feasibility of high-frequency, low TCF electroacoustic micro-resonator based on SOI and piezoelectric thin film technology was demonstrated by the present simulation study.

Using intrinsic zero to notch satellite signals in UWB filter

In this paper, an ultra-wideband (UWB) filter with a notch band using T-shaped step impedance resonator loaded with cross-shaped open stubs has been presented. The notch band is formed by utilizing intrinsic zero. The characteristics of the new quad-mode resonator have been analyzed using odd-even mode analysis method. It can be shown that it is the intrinsic zero that generates the notch band. In addition, wide tunable notch band form 5–9.3 GHz can be achieved. A UWB filter with a notch band centered at 6.25 GHz using the proposed quad-mode resonator has been designed, fabricated, and tested. Experiment results show that the attenuation in notch frequency is >22 dB while the return loss of the simulation and measurement results are 22 dB/20 dB and 14.5 dB/11.2 dB in the lower and upper passband, respectively, which illustrate that the simulation and measurement results are in agreement.

{0,1} completely positive tensors and multi-hypergraphs

Completely positive graphs have been employed to associate with completely positive matrices for characterizing the intrinsic zero patterns. As tensors have been widely recognized as a higher-order extension of matrices, the multi-hypergraph, regarded as a generalization of graphs, is then introduced to associate with tensors for the study of complete positivity. To describe the dependence of the corresponding zero pattern for a special type of completely positive tensors—the {0,1} completely positive tensors, the completely positive multi-hypergraph is defined. By characterizing properties of the associated multi-hypergraph, we provide necessary and sufficient conditions for any (0,1) associated tensor to be {0,1} completely positive. Furthermore, a necessary and sufficient condition for a uniform multi-hypergraph to be a completely positive multi-hypergraph is proposed as well.

Half-metallic Dirac cone in zigzag graphene nanoribbons on graphene

The Dirac electrons of graphene, an intrinsic zero gap semiconductor, uniquely carry spin and pseudospin that give rise to many fascinating electronic and transport properties. While isolated zigzag graphene nanoribbons are antiferromagnetic semiconductors, we show by means of first-principles and tight-binding calculations that zigzag graphene nanoribbons supported on graphene are half-metallic as a result of spin- and pseudospin-symmetry breaking. In particular, half-metallic Dirac cones are formed at K (K') near the Fermi level. The present results demonstrate that the unique combination of spin and pseudospin in zigzag graphene nanoribbons may be used to manipulate the electronic properties of graphene, and may have practical implications for potential graphene-based nanoelectronic applications.

Investigations of touchscreen glasses from mobile phones for retrospective and accident dosimetry

Touchscreen glasses of mobile phones are sensitive to ionizing radiation and have the potential of usage as an emergency dosimeter for retrospective dosimetry for the purpose of triage after a radiological accident or attack. In this study the TL glow curves and dosimetric properties of touchscreen glasses were studied in detail, such as intrinsic background dose, dose response, reproducibility, optical stability and long-term stability of the TL signal.Preliminary results are additionally presented to minimize the intrinsic background dose by mechanically removing the surface layer of the glass samples. Additionally chemical element analyses of the touchscreen glass samples were carried out to investigate the difference between glass samples which show a TL signal and samples which show neither an intrinsic zero dose signal nor a radiation induced TL signal.An irradiation trial using glass samples stored in the dark demonstrated a successful dose recovery. However, when applying a realistic, external light exposure scenario, dose underestimation was observed, even though samples were pre-bleached prior to measurement. More investigations have to be carried out in the future to solve the challenge of the low optical stability of the TL signal, if touchscreen glasses are to be used as a reliable emergency dosimeter.

Improving the efficiency of hierarchical equations of motion approach and application to coherent dynamics in Aharonov-Bohm interferometers.

Several recent advancements for the hierarchical equations of motion (HEOM) approach are reported. First, we propose an a priori estimate for the optimal number of basis functions for the reservoir memory decomposition. Second, we make use of the sparsity of auxiliary density operators (ADOs) and propose two ansatzs to screen out all the intrinsic zero ADO elements. Third, we propose a new truncation scheme by utilizing the time derivatives of higher-tier ADOs. These novel techniques greatly reduce the memory cost of the HEOM approach, and thus enhance its efficiency and applicability. The improved HEOM approach is applied to simulate the coherent dynamics of Aharonov-Bohm double quantum dot interferometers. Quantitatively accurate dynamics is obtained for both noninteracting and interacting quantum dots. The crucial role of the quantum phase for the magnitude of quantum coherence and quantum entanglement is revealed.

Design of Ultra-Wideband Bandpass Filters With Fixed and Reconfigurable Notch Bands Using Terminated Cross-Shaped Resonators

In this paper, a novel terminated cross-shaped resonator (TCSR) is analyzed and used to design ultra-wideband (UWB) bandpass filters (BPFs) with fixed and reconfigurable notch bands. It is found that the TCSR can exhibit a maximum three poles and two zeros when open and short terminations are applied. The intrinsic zero is simply used for the implementation of notch bands offering systematic design and flexible tuning capabilities. Bandwidth can also be kept unchanged when tuning a notch within the UWB passband. In contrast to common band-notched UWB BPFs using additional notch resonators, only a single TCSR is required to realize band-notched UWB filters. Three UWB BPF prototypes, including a four-pole filter with 94.7% fractional bandwidth (FBW) and a notch band at 5.8 GHz, a five-pole filter with 111% FBW and dual notch bands at 4.3/9.1 GHz, and a four-pole filter with 82.4% FBW and reconfigurable notch band from 4.6 to 6.5 GHz are designed and experimentally characterized. Their experimental characterizations are in good agreement with theoretical analysis validating a simple approach of band-notched UWB BPF design.

Evaluation of Defiberation by Organosolv Ethanolamine Pulping for Integral Utilization of Oil Palm EFB

Organosolv ethanolamine pulping for oil palm empty fruit bunches(EFB) were evaluated in this study. The screen yield by the ethanolamine pulping were higher than that by the soda pulping at the same operation conditions. The higher concentration of ethanolamine solvent resulted in the higher yield and the lower contents of residual lignin. The EFB pulp fibers were the narrower in fiber width but the higher in coarseness than those of the hardwood pulp fiber, while the fiber length of the EFB pulp fiber were similar to that of the hardwood fiber. The intrinsic zero span tensile testing showed the EFB pulp fiber by the 80% ethanolamine pulping were the stronger than the fiber by the soda pulping. The results of this study supported that the ethanolamine pulping could be used as an alternative pulping method for the EFB.

Focusing on Energy and Optoelectronic Applications: A Journey for Graphene and Graphene Oxide at Large Scale

Carbon is the only element that has stable allotropes in the 0th through the 3rd dimension, all of which have many outstanding properties. Graphene is the basic building block of other important carbon allotropes. Studies of graphene became much more active after the Geim group isolated "free" and "perfect" graphene sheets and demonstrated the unprecedented electronic properties of graphene in 2004. So far, no other individual material combines so many important properties, including high mobility, Hall effect, transparency, mechanical strength, and thermal conductivity. In this Account, we briefly review our studies of bulk scale graphene and graphene oxide (GO), including their synthesis and applications focused on energy and optoelectronics. Researchers use many methods to produce graphene materials: bottom-up and top-down methods and scalable methods such as chemical vapor deposition (CVD) and chemical exfoliation. Each fabrication method has both advantages and limitations. CVD could represent the most important production method for electronic applications. The chemical exfoliation method offers the advantages of easy scale up and easy solution processing but also produces graphene oxide (GO), which leads to defects and the introduction of heavy functional groups. However, most of these additional functional groups and defects can be removed by chemical reduction or thermal annealing. Because solution processing is required for many film and device applications, including transparent electrodes for touch screens, light-emitting devices (LED), field-effect transistors (FET), and photovoltaic devices (OPV), flexible electronics, and composite applications, the use of GO is important for the production of graphene. Because graphene has an intrinsic zero band gap, this issue needs to be tackled for its FET applications. The studies for transparent electrode related applications have made great progress, but researchers need to improve sheet resistance while maintaining reasonable transparency. Proposals for solving these issues include doping or controlling the sheet size and defects, and theory indicates that graphene can match the overall performance of indium tin oxide (ITO). We have significantly improved the specific capacitance in graphene supercapacitor devices, though our results do not yet approach theoretical values. For composite applications, the key issue is to prevent the restacking of graphene sheets, which we achieved by adding blocking molecules. The continued success of graphene studies will require further development in two areas: (1) the large scale and controlled synthesis of graphene, producing different structures and quantities that are needed for a variety of applications and (2) on table applications, such as transparent electrodes and energy storage devices. Overall, graphene has demonstrated performance that equals or surpasses that of other new carbon allotropes. These features, combined with its easier access and better processing ability, offer the potential basis for truly revolutionary applications and as a future fundamental technological material beyond the silicon age.

Scaling of Excitons in Graphene Nanoribbons with Armchair Shaped Edges

The scaling behavior of band gaps and fundamental quantities of exciton, i.e., reduced mass, size, and binding strength, in three families of quasi one-dimensional graphene nanoribbons with hydrogen passivated armchair shaped edge (AGNRs) are comprehensively investigated by density functional theory with quasi-particle corrections and many body, i.e., electron-hole, interactions. Compared with single-walled carbon nanotubes (SWCNTs) where the scaling character features a single exponent, each family of AGNRs has its own single exponent, due to its intrinsic zero curvature, which also accounts for the absent "family spreading" of optical transition energies in the smaller width region in the Kataura plots of AGNRs as compared to those of SWCNTs. Moreover, the scaling relation between exciton binding strength and the geometric parameter is established.