bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced cyber‐physical security using attack‐resistant cyber nodes and event‐triggered moving target defence
Authors: Higgins Martin , Mayes Keith , Teng Fei
Published: March 2021

A cyber‐physical authentication strategy to protect power system infrastructure against false data injection (FDI) attacks is outlined. The authors demonstrate that it is feasible to use small, low‐cost, yet highly attack‐resistant security chips as measurement nodes, enhanced with an event‐triggered moving target defence (MTD), to offer effective cyber‐physical security. At the cyber layer, the proposed solution is based on the MULTOS Trust‐Anchor chip, using an authenticated encryption protocol, offering cryptographically protected and chained reports at up to 12/s. The availability of the Trust‐Anchors allows the grid controller to delegate aspects of passive anomaly detection, supporting local as well as central alarms. In this context, a distributed event‐triggered MTD protocol is implemented at the physical layer to complement cyber side enhancement. This protocol applies a distributed anomaly detection scheme based on Holt‐Winters seasonal forecasting in combination with MTD implemented via inductance perturbation. The scheme is shown to be effective at preventing or detecting a wide range of attacks against power system measurement system.
The star catalogue of Wilhelm IV, Landgraf von Hessen-Kassel
Authors: Verbunt Frank , Schrimpf Andreas
Published: March 2021

We analyse a manuscript star catalogue by Wilhem IV, Landgraf von Hessen-Kassel from 1586. From measurements of altitudes and of angles between stars, given in the catalogue, we find that the measurement accuracy averages 26″ for eight fundamental stars, compared to 49″ of the measurements by Brahe. The computation in converting altitudes to declinations and angles between stars to celestial positions is very accurate, with errors that are negligible with respect to the measurement errors. Due to an offset in the position of the vernal equinox, the positional error of the catalogue is slightly worse than that of Brahe’s catalogue; however, when a correction is made for the offset, which was known to 17th century astronomers, the catalogue is more accurate than that of Brahe by a factor of two. We provide machine-readable tables of the catalogue.
Analysis of Green House Gases and Positive Impact of Replacing Traditional Energy with Clean Energy
Authors: Kuang Chengyu
Published: March 2021

In this study, the potential sources and detrimental effects that will be caused by the several green house gases are firstly presented. The exact proportions of the green house gas, produced from fossil fuel and the exact proportions of the green house gas that is produced naturally are found out. Next, the author finds out the green house gases that contribute the most to the global warming and their causes. Therefore the proportion of the green house gas that is emitted by the developing countries is found out. In addition, the exact proportion and the amount of sustainable energy that are used to generate electricity in some representative developing countries are analyzed. Subsequently, the author proposes a hypothesis that if these countries have 20% of clean energy usage in their gross energy consumption, the five representatives effects, which are caused by the green house effect will be mitigated. The result shows that these effects will be mitigated with different extents.
Overview of Maximum Power Point Tracking Techniques for PV System
Authors: Fahim Khairul Eahsun , Farabi Shaikh M , Farhan Shaikh Shahrukh , Esha Ishrat Jahan , Muhtadi Taseen
Published: March 2021

Fossil fuel is one of the major sources of the world’s energy generation. Greenhouse gases are increasing in the atmosphere due to the excessive use of fossil fuels. To tackle global warming and the shortage of natural gases, researchers are always looking for alternative sources of clean energy. Solar energy is becoming popular due to its inexhaustible nature. To get the most of out of a solar system and to generate maximum power, it is important to operate the panel at maximum power point. In other words, it can be said that MPP techniques are used to maximize the output power. There is a wide range of MPPT algorithm available to calculate MPP. This paper gives a broad overview of the existing MPPT techniques used in practice.
Weighted Islanding Detection for DC Microgrid Based on Random Forest Classification
Authors: Wan Qingzhu , Wu Kaicong
Published: March 2021

At present, the main form of microgrid is AC grid. DC microgrids have received extensive attention and research with the rapid development of various DC power. The operation mode of the DC microgrid is divided into grid-connected operation and islanding operation. Islanding is formed after the circuit breaker tripped, which connects microgrid to large grid. Islanding operation can be divided into planned islanding and unplanned islanding. Unplanned islanding will cause certain harm to users and systems, so it is necessary to detect islanding accurately in the DC microgrid. This paper proposes an islanding detection method for DC microgrid based on random forest classification. Firstly, raw data is cleaned, extracted features and generated feature vector set. The extracted features include six islanding characteristic indexes, which consist of voltage, current, output active power and their first order backward difference on the DC bus side. Then, based on random forest classification, building the islanding detection model. Islanding detection model for DC microgrid can distinguish islanding event successfully and accurately. Based on weighted random forest classification, it can detect islanding event more accurately compared with decision tree classification when processing large amounts of data.
Künstliche Intelligenz in der Radiologie: Wo stehen wir? Wo kann es hingehen?
Authors: Vogl Thomas J. , Mader Christoph , Booz Christian , Koch Vitali , Bernatz Simon
Published: March 2021

Neben der stetig zunehmenden Arbeitsverdichtung wird die Diagnostik und Patientenbetreuung für MTRA und Radiologen immer komplexer. Als potenziellen Lösungsansatz dieser täglichen Herausforderungen im Gesundheitswesen hat das Thema Künstliche Intelligenz längst Aufmerksamkeit auf sich gezogen und bereits viele Debatten über die Rolle und Verantwortlichkeiten des Radiologen und der MTRA ausgelöst.
Update Mammakarzinom 2020 Teil 3 – frühes Mammakarzinom
Authors: Huober Jens , Schneeweiss Andreas , Hartkopf Andreas D. , Müller Volkmar , Lux Michael P. , Janni Wolfgang , Ettl Johannes , Belleville Erik , Thill Marc , Fasching Peter A. , Kolberg Hans-Christian , Schulmeyer Carla E. , Welslau Manfred , Overkamp Friedrich , Tesch Hans , Fehm Tanja N. , Lüftner Diana , Schütz Florian , Wöckel Achim
Published: March 2021

Die Therapie von Patientinnen mit frühem Mammakarzinom war immer schon geprägt von Eskalation durch neue Therapien und Deeskalation durch Identifikation besserer Therapieschemata oder Einführung von besseren Werkzeugen zur Einschätzung der Prognose. Die Anstrengungen der letzten Jahre haben auf einigen dieser Gebiete zu einer soliden Datenlage geführt. Die Ergebnisse der großen Deeskalationsstudien durch Nutzung von Multi-Gen-Tests liegen ebenso vor wie die Ergebnisse einiger Studien, die die neuen Anti-HER2-Substanzen T-DM1 und Pertuzumab in der frühen Therapiesituation untersucht haben. Mehrere groß angelegte Studien zur Untersuchung der Rolle der CDK4/6-Inhibitoren stehen kurz vor dem Abschluss, sodass auch in dieser Therapiesituation mit Neuerungen zu rechnen ist. Diese Übersichtsarbeit soll die Ergebnisse der neuesten Publikationen zusammenfassen und einordnen.
Adipositas im Kindes- und Jugendalter – Kardiovaskuläre Implikationen für die Zukunft
Authors: Stein Robert , Kiess Wieland , Körner Antje
Published: March 2021

Adipositas und assoziierte kardiovaskuläre Risikofaktoren, wie arterielle Hypertonie, Dyslipidämie, Hyperinsulinämie und gestörte Glukosetoleranz, entstehen häufig bereits in der Kindheit und legen somit den Grundstein für Herz-Kreislauf-Erkrankungen im Erwachsenenalter. Gleichwohl lassen sich Folgeschäden wie endotheliale Dysfunktion, Arteriosklerose und kardiales Remodeling bereits in dieser frühen Lebensphase nachweisen. Die Risikofaktoren zeigen eine hohe Stabilität bis in das Erwachsenenalter hinein und führen in ihrer langfristigen Akkumulation zur Ausprägung kardiovaskulärer Ereignisse. Auch wenn eine Gewichtsreduktion nur in seltenen Fällen gelingt, sollte eine konsequente Therapie der Adipositas und ihrer Komorbiditäten frühzeitig versucht werden, da eine Remission während der Kindheit das Risiko für kardiovaskuläre Folgen im Erwachsenenalter auf ein Niveau senkt, welches vergleichbar mit dem der schlanken Normalbevölkerung ist.
Ruheinseln schaffen – Ängsten trotzen
Authors: Freitag-Herse Barbara
Published: March 2021

Die Corona-Pandemie ist für die meisten Menschen eine echte Herausforderung. Das Infektionsrisiko und die Sorge um den Arbeitsplatz lösen bei vielen Angst aus. Als Führungskraft sind Sie besonders gefordert, wenn es darum geht, die Angst nicht das Handeln bestimmen zu lassen. Um das zu erreichen, gibt es ein paar einfache, aber wirkungsvolle Dinge, die Sie gemeinsam mit Ihren Mitarbeitenden tun können.
E wie Ethik – Warum Reflexion und Austausch von beruflichem Handeln wichtig sind
Authors: Kühnast Petra
Published: March 2021

Ethische Themen führen in der Physiotherapie oft ein stiefmütterliches Dasein. Dabei gibt es zahlreiche Situationen, in denen Therapeuten abwägen müssen und sich in einem inneren Spagat befinden. Physiotherapie und Ethik zu verknüpfen, kann den Wert der Therapie steigern.
Cross-Cultural Adaptation and Validation of the Translated Patient-Rated Wrist Evaluation Score
Authors: Gómez-Eslava Bárbara , Rodriguez-Ricardo Maria Cristina , Serpa Juan Camilo , Fajury Raschid , García-González Luis A.
Published: March 2021

Introduction The purpose of this study is to perform a cross-cultural adaptation and validation of the translated Patient-Rated Wrist Evaluation (PRWE) score exclusively for pathologies of the wrist.

Materials and Methods A methodological study of cross-cultural validation of clinical scores was performed through a test–retest reliability analysis, internal consistency, response to change, and criterion validity assessment.

Results The test was applied to 57 patients with 139 surveys. Stability evaluated through Lin's concordance correlation coefficient was 0.98, with 95% confidence interval (CI) = 0.97–0.99; Cronbach's alpha was > 0.91; the difference in score was 24.26 (standard deviation: 26.59); the standardized response mean was 0.912; the effect size was 0.924; the Spearman's coefficient between the differences of PRWE and DASH—Disabilities of the Arm, Shoulder, and Hand—scores was r = 0.899, with 95% CI = 0.811–0.947; Spearman's nonparametric correlation test between PRWE and DASH was 0.82, with 95% CI = 0.711–0.890.

Conclusions We successfully validated the Spanish translation of the PRWE scale. It showed valid and reliable interpretation of functional status and response to treatment after distal radius fracture, for Colombian population.

Level of Evidence This is a level II, methodological study for scale validation.
Interview: Es gibt mehr Corona-Helden als nur die Intensivstationen
Authors: Heeser Alexandra
Published: March 2021

In Baden-Württemberg gehören auch größere solitäre, gemischte Einrichtungen in die Landeskrankenhausplanung für die Phase B der neurologischen Früh-Reha – nicht nur Akutkliniken. Das hatte und hat auch Auswirkung auf die Verteilung der Corona-Patienten. „Unter DRG-Gesichtspunkten hat kaum ein Krankenhaus Interesse, einen langfristig beatmeten noch intensivpflegebedürftigen, aber auch gleichzeitig schon therapiebedürftigen Patienten im IMC- oder Intensiv-Setting zu behandeln“, erklärt Daniel Charlton Geschäftsführer der BDH-Klinik Elzach gGmbH.
Türmanagement: Im Notfall muss es schnell gehen
Authors: Lang Michael
Published: March 2021

Fluchttüren verrichten unauffällig ihren Dienst im Krankenhaus. Sicherheitsexperte Jörg Bärenfänger erklärt im Interview die gesetzlichen und technischen Anforderungen an die Systeme, und informiert über aktuelle Trends.
Creating plasma from foam using high-energy lasers
Authors: McConnon Aili
Published: March 2021

Studying the transition of foam into the plasma state can lead to applications such as charged particle acceleration with lasers and creating strong shock waves with radiation-controlled energy transport.
Elastocaloric material shows promise for environmentally friendly refrigeration applications
Authors: McConnon Aili
Published: March 2021

A cobalt-vanadium–gallium-based alloy achieves a large elastocaloric effect and excellent cyclability.
Tabletop X-ray spectroscopy probes electron dynamics on attosecond timescales
Authors: Johnson-Groh Mara
Published: March 2021

Ultrahigh time resolution tabletop X-ray spectroscopy is poised to further understanding of quantum materials, light harvesting devices, and ultrafast electronics.
Inviting others to life in reciprocal space
Authors: Lind C.
Published: March 2021

Crystallography is an important science that impacts many areas of research. The number of users of crystallographic techniques has increased significantly over the past few decades, as diffractometers have become readily available and many commercial programs with user-friendly interfaces have been developed. The growth in computing power has led to the development of advanced methods that were unthinkable in the past. Yet at the same time, formal crystallography teaching has declined, with many programs no longer offering formal crystallography classes. This combination has resulted in many avoidable errors in data collection, processing, and interpretation of results. Making crystallographic teaching, both of theoretical concepts and hands-on training in data processing and analysis, available to the next generation of crystallographers is a crucial mandate. This paper gives a glimpse at several possible avenues to invite newcomers to a successful life in reciprocal space.
Magnetic perturbations of anyonic and Aharonov–Bohm Schrödinger operators
Authors: Correggi Michele , Fermi Davide
Published: March 2021

We study the Hamiltonian describing two anyons moving in a plane in the presence of an external magnetic field and identify a one-parameter family of self-adjoint realizations of the corresponding Schrödinger operator. We also discuss the associated model describing a quantum particle immersed in a magnetic field with a local Aharonov–Bohm singularity. For a special class of magnetic potentials, we provide a complete classification of all possible self-adjoint extensions.
Self-aligned gates for scalable silicon quantum computing
Authors: Geyer Simon , Camenzind Leon C. , Czornomaz Lukas , Deshpande Veeresh , Fuhrer Andreas , Warburton Richard J. , Zumbühl Dominik M. , Kuhlmann Andreas V.
Published: March 2021

Silicon quantum dot spin qubits have great potential for application in large-scale quantum circuits as they share many similarities with conventional transistors that represent the prototypical example for scalable electronic platforms. However, for quantum dot formation and control, additional gates are required, which add to device complexity and, thus, hinder upscaling. Here, we meet this challenge by demonstrating the scalable integration of a multilayer gate stack in silicon quantum dot devices using self-alignment, which allows for ultra-small gate lengths and intrinsically perfect layer-to-layer alignment. We explore the prospects of these devices as hosts for hole spin qubits that benefit from electrically driven spin control via spin–orbit interaction. Therefore, we study hole transport through a double quantum dot and observe current rectification due to the Pauli spin blockade. The application of a small magnetic field leads to lifting of the spin blockade and reveals the presence of spin–orbit interaction. From the magnitude of a singlet-triplet anticrossing at a high magnetic field, we estimate a spin–orbit energy of ∼37μeV, which corresponds to a spin–orbit length of ∼48 nm. This work paves the way for scalable spin-based quantum circuits with fast, all-electrical qubit control.
Localization-delocalization effects of a delocalizing dissipation on disordered XXZ spin chains
Authors: Xu Xiansong , Poletti Dario
Published: March 2021

The interplay between interaction, disorder, and dissipation has shown a rich phenomenology. Here, we investigate a disordered XXZ spin chain in contact with a bath which, alone, would drive the system toward a highly delocalized and coherent Dicke state. We show that there exist regimes for which the natural orbitals of the single-particle density matrix of the steady state are all localized in the presence of strong disorders, for either weak interaction or strong interaction. We show that the averaged steady-state occupation in the eigenbasis of the open system Hamiltonian could follow an exponential decay for intermediate disorder strength in the presence of weak interactions, while it is more evenly spread for strong disorder or for stronger interactions. Last, we show that strong dissipation increases the coherence of the steady states, thus reducing the signatures of localization. We capture such signatures of localization also with a concatenated inverse participation ratio that simultaneously takes into account how localized are the eigenstates of the Hamiltonian and how close is the steady state to an incoherent mixture of different energy eigenstates.
Analytical survey of the predator–prey model with fractional derivative order
Authors: Abbagari Souleymanou , Houwe Alphonse , Saliou Youssoufa , Douvagaï  , Chu Yu-Ming , Inc Mustafa , Rezazadeh Hadi , Doka Serge Y.
Published: March 2021

This work addresses the analytical investigation of the prey–predator behavior modeled by nonlinear evolution equation systems with fractional derivative order. Through the New Extended Algebraic Method (NEAM), we unearthed diverse types of soliton solutions including bright, dark solitons, combined trigonometric function solutions, and singular solutions. Besides the results obtained in the work of Khater, some new complex soliton solutions are also unearthed. The NEAM can also be used like the synthesis of the two mathematical tools.
Acoustoelastic phononic metamaterial for isolation of sound and vibrations
Authors: Aravantinos-Zafiris Nikos , Kanistras Nikos , Sigalas Mihail M.
Published: March 2021

In this work, a phononic metamaterial that could be applied for both acoustic and elastic wave attenuation is numerically examined. The hollow yablonovite structure with the addition of hollow spheres on a face-centered cubic arrangement is examined numerically, and wide bandgaps are found for the propagation of acoustic and elastic waves. The calculations were performed by using the finite element method. The research includes an investigation of all the geometric parameters of the structure and how the bandgaps are being affected from the values of each parameter. The proposed structure is found to have wide bandgaps for both elastic and acoustic waves. These findings strongly indicate that the proposed acoustoelastic metamaterial is a powerful candidate for several applications such as sound and vibrations attenuation, noise reduction, and acoustic filtering.
Conceptual design of magnetic force control system using wedge mechanism
Authors: Wang ALong , Park So-Hee , Noh Myounggyu , Park Young-Woo
Published: March 2021

This paper presents a conceptual design and proof-of-concept to control magnetic force using a wedge mechanism. The concept starts with the general knowledge that magnetic force is inversely proportional to distance. A magnetic model is generated consisting of a permanent magnet (PM), two magnetic flux paths, two wheels, and a steel plate. This model is subjected to formulate a mathematical relationship between the movement of the PM and a magnetic force exerted onto the steel plate. A 3D simulation has been conducted to verify the effectiveness of the developed mathematical model. The comparison between the mathematical and simulation models is likely to be fair. The next is to design a wedge mechanism which is composed of two wedges, a trenching plate, and a stepping motor. Finally, the proof-of-concept is placed on a magnetic force measurement and subjected to experiments. The result shows that the changes in the magnetic force according to the PM movements are 84.5% with simulation and 80.1% with the experiments, respectively. It can be concluded that the proposed concept is effective in reasonably controlling the magnetic force.
Structure of human Na
v
1.5 reveals the fast inactivation-related segments as a mutational hotspot for the long QT syndrome
Authors: Li Zhangqiang , Jin Xueqin , Wu Tong , Zhao Xin , Wang Weipeng , Lei Jianlin , Pan Xiaojing , Yan Nieng
Published: March 2021

Significance

Dysfunction of Na
v
1.5, the primary cardiac Na
v
channel, is associated with multiple arrhythmia syndromes, exemplified by type 3 long QT syndrome (LQT3) and Brugada syndrome (BrS). Establishment of the structure-function relationship and mechanistic understanding of the disease variants will facilitate the development of antiarrhythmic drugs. Here we report the cryo-EM structure of human Na
v
1.5-E1784K, the most common variant shared by LQT3 and BrS. Structural mapping of 91 LQT3-associated mutations reveal a hotspot that involves the fast inactivation segments. The high density of LQT3 mutation sites in this region can be reasonably interpreted by the “door wedge” model for fast inactivation, which was derived from our previous structural observations and is supported by a wealth of functional characterizations.
30 years of observations and hopes for faster progress on promoting the status of women in science
Authors: Randolph Gwendalyn J.
Published: March 2021

Gwendalyn Randolph shares her observations and ideas for how institutions can partner with women to support their careers in STEM.
Modelling of a soft tunable lens actuated by an annular dielectric elastomer actuator with homogeneous and inhomogeneous prestretches
Authors: Shi Huiqi , Wang Huiming
Published: March 2021

Unlike the conventional tunable lens which contains cumbersome elements to fulfill the focus adjustment, soft liquid lens shows distinct advantages in compactness and flexibility. This paper presents a computational model of a dielectric elastomer (DE)-based, liquid-coupled soft tunable lens. The vital component of the lens system is a DE film which is divided into lens part and actuation part. The actuation part is annular which is coated with compliant electrodes while the lens part is circular and uncoated. A fixed volume of glycerol is injected into the lens to act as a transparent medium. An applied voltage will trigger the transmission of liquid between the two parts and eventually change the focal length. Governing equations for the two parts are established and the shooting method with two initial guesses is developed to solve the boundary value problems. The simulation results agree well with the experimental data. Several parametric analyses are carried out based on the developed model. It is found that the film thickness, initial volume of the liquid, the prestretch, and areas of the two parts all have significant effects on the focusing ability of the tunable lens. Both the homogeneous and inhomogeneous prestretched schemes are considered. An inhomogeneous prestretch on the annular actuation part is beneficial for improving the focusing ability of the tunable lens.
Numerical investigation of ion collection by a planar probe in stationary and parallel flowing plasmas
Authors: Zhang Kai , Wang Weizong , Cai Guobiao
Published: March 2021

3D hybrid particle-in-cell simulations were performed to investigate the ion current collection behavior by a thin double-sided circular planar probe in both stationary and parallel flowing plasmas with cold ions and Boltzmann electrons. Results for stationary plasma cases showed that the assumption of a constant ion density ratio at the sheath boundary to that of unperturbed plasma is inaccurate for planar probes for probe radii from 10 to 30 Debye length and probe biases from −5 to −30 times the electron temperature. The flowing plasma results showed that ion current strongly depends on the parallel flowing velocity, contrary to earlier models. The collected ion current decreases with increasing parallel velocity, reaching a minimum at around ion sound speed, then slowly recovers and even exceeds the value of the stationary case at high flow speed. The deviation of ion current due to parallel flow from stationary case could be −35% to +20% for flowing plasmas with flow speed comparable to ion sound speed. Therefore, it is important to consider the flow impact on ion collection when using planar probes in such circumstances, e.g. electric propulsion plume measurements. The mechanism for this behavior is qualitatively investigated and discussed.
Ion irradiation induced strain and structural changes in LiTaO3 perovskite*
Authors: Zhang F X , Velisa G , Xue H , Sellami N , Trautmann C , Zhang Y , Weber W J
Published: March 2021

LiTaO3 crystals irradiated with 3 MeV and 1.162 GeV Au ions were studied by single crystal x-ray diffraction and Raman scattering measurements. The maximum lattice strains after 3 MeV Au ion irradiation to a fluence of 1.2 × 1013 cm−2 were 1.2% and 0.6% along the c- and a-/b-axes, respectively. Two effects were observed in 1.162 GeV Au ion irradiated samples: (i) the (0006) and (1120) Bragg peaks were split into doublets, which suggested a subtle structural change due to slight modification of chemical composition; and (ii) the pre-damaged 1.2% lattice strain along the c-axis was relaxed to 0.9% after subsequent irradiation with 1.162 GeV Au ions, while relaxation along the a- or b-axis was not obvious. A distinct change in the Raman spectrum of the 〈0001〉 oriented LiTaO3 crystals was observed after 1.162 GeV Au ion irradiation, but no obvious change was observed in the 〈1120〉 oriented samples or in 3 MeV Au ion irradiated samples. Strain and structural changes in crystalline LiTaO3, with or without pre-existing defects, upon ion irradiation are delineated in its responding to inelastic ionization and elastic nuclear collisions.
Mobility edges in one-dimensional models with quasi-periodic disorder
Authors: Tang Qiyun , He Yan
Published: March 2021

We study the mobility edges in a variety of one-dimensional tight binding models with slowly varying quasi-periodic disorders. It is found that the quasi-periodic disordered models can be approximated by an ensemble of periodic models. The mobility edges can be determined by the overlaps of the energy bands of these periodic models. We demonstrate that this method provides an efficient way to find out the precise location of mobility edge in quasi-periodic disordered models. Based on this approximate method, we also propose an index to indicate the degree of localization of each eigenstate.
Impact of a contrast-to-noise ratio driven and material specific exposure control on image quality and radiation exposure in angiography
Authors: Werncke Thomas , Kemling Marius , Tashenov Stanislav , Hinrichs Jan B , Meine Timo C , Maschke Sabine K , Kyriakou Yiannis , Wacker Frank K , Meyer Bernhard C
Published: March 2021

Conventional detector-dose driven exposure controls (DEC) do not consider the contrasting material of interest in angiography. Considering the latter when choosing the acquisition parameters should allow for optimization of x-ray quality and consecutively lead to a substantial reduction of radiation exposure. Therefore, the impact of a material-specific, contrast-to-noise ratio (CNR) driven exposure control (CEC) compared to DEC on radiation exposure was investigated. A 3D-printed phantom containing iron, tantalum, and platinum foils and cavities, filled with iodine, barium, and gas (carbon dioxide), was developed to measure the CNR. This phantom was placed within a stack of polymethylmethacrylate and aluminum plates simulating a patient equivalent thickness (PET) of 2.5–40 cm. Fluoroscopy and digital radiography (DR) were conducted applying either CEC or three, regular DEC protocols with parameter settings used in abdominal interventions. CEC protocols where chosen to achieve material-specific CNR values similar to those of DEC. Incident air kerma at the reference point(Ka,r), using either CEC or DEC, was assessed and possible Ka,r reduction for similar CNR was estimated. We show that CEC provided similar CNR as DEC at the same or lower Ka,r. When imaging barium, iron, and iodine Ka,r was substantially reduced below a PET of 20 cm and between 25 cm and 30 cm for fluoroscopy and Dr When imaging platinum and tantalum using fluoroscopy and DR and gas using DR, the Ka,r reduction was substantially higher. We estimate the Ka,r reduction for these materials between 15% and 84% for fluoroscopy and DR between 15% and 93% depending on the PET. The results of this study demonstrate a high potential for skin dose reduction in abdominal radiology when using a material-specific CEC compared to DEC. This effect is substantial in imaging materials with higher energy K-edges, which is beneficial, for example, in long-lasting embolization procedures with tantalum-based embolization material in young patients with arterio-venous malformations.
Design and analysis of piezoelectric micromachined ultrasonic transducer using high coupling PMN-PT single crystal thin film for ultrasound imaging
Authors: Chen Mingzhu , Zhang Qiaozhen , Zhao Xiangyong , Wang Feifei , Liu Huiling , Li Baichuan , Zhang Xiangfen , Luo Haosu
Published: March 2021

Due to its higher frequency, improved impedance matching, and easy formation of array, piezoelectric micromachined ultrasonic transducer (PMUT) has drawn much attentions for application in ultrasound imaging. In this paper, PMUT based on [011] poled 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 (PMN-0.30PT) single crystal thin film was proposed and modeled by performing finite element method. Influences of different configurations of top electrode shape and bottom cavity shape on PMUT performance were studied. The investigation results show that the resonant frequency of PMN-PT-based PMUT with circular top electrode and square bottom cavity is up to 27.155 MHz. The effective electromechanical coupling coefficient (

k

eff

2

)

of PMUT was up to 2.32%, which was 127% larger than that of lead zirconate titanate-based PMUT. The static transmitting sensitivity was three times enhancement compared to PMUT with square top electrode and square bottom cavity. Furthermore, acoustic field characteristics of PMUT and PMUT arrays based on PMN-PT in water were investigated. The relative pulse-echo sensitivity level of 2 × 2 PMUT array was −35 dB with the reflector at 200 μm. The obtained results demonstrated that the proposed PMN-PT-based PMUT can achieve high frequency and large

k

eff

2

as well as considerable sensitivity, which is promising for application in high resolution ultrasound imaging.
Impact of helical electromagnetic fields on the axion window
Authors: Kobayashi Takeshi , Jain Rajeev Kumar
Published: March 2021

Primordial electromagnetic fields can strongly affect the
cosmic evolution of axions, and vice versa. We show that if helical
electromagnetic fields are coherently produced in the early
universe, their remnants source a field velocity to the coupled
axions and enhance the relic abundance of axion dark matter. We
discuss the implications for the QCD axion and axion-like particles
that are coupled to the SM or hidden gauge groups. For a QCD axion
coupled to hidden photons, we find that the conventional window for
the axion decay constant 108 GeV≲ f ≲
1012 GeV can be completely closed due to
overproduction of axion dark matter by helical electromagnetic
fields as little as α Δ Neff≳
10-12, where α is the gauge coupling and Δ
N_eff is the effective extra relativistic degrees of
freedom of the hidden photons.
Continuous and discontinuous waves in an ASEP with pockets
Authors: Humenyuk Yosyp A , Kotrla Miroslav , Slanina František
Published: March 2021

We consider a geometric modification of the asymmetric simple exclusion process model in which each site of a one-dimensional chain is attached to a lateral dead-end site. Since it has an uncorrelated steady state, this model shows rich density profile dynamics over large distances and timescales. We analyse various waves emerging from initial step-wise profiles. The most interesting feature is that this model demonstrates travelling rarefaction and contraction waves with a discontinuity at the leading edge.
Wind Tunnel Testing Study of Segmented Slat with Simulated Icing for Civil Aircraft
Authors: Liu Yang , Zhou Xing
Published: March 2021

Icing accretion on civil aircraft have a severe impact on safety and performance, and the leading edge icing of wing resulting in maximum lift coefficient reduction, drag increasing, stalling incidence forward, control and stability worsening and even stalling. This article is to explore aerodynamic characteristics variation of civil aircraft with simulated icing accretion on different segmented slats through the means of wind tunnel testing, and the typical aerodynamic characteristic parameters involve maximum lift coefficient, stalling incidence and lift-to-drag ratio. Forces and moments measurement for configurations of the cruising, take-off and landing had been carried out, the results and analysis of testing data could be used for anti-icing design and operation strategy making.
Attention-based Machine Learning Model for Smart Contract Vulnerability Detection
Authors: Sun Yuhang , Gu Lize
Published: March 2021

Ethereum attracts extensive attention due to its distinctive function of smart contract and decentralized applications (Dapps). Since the number of contracts on blockchain has increased vigorously, various security vulnerabilities come up. Researchers rely on static symbolic analysis method at first, and it seems to perform well in the accuracy of vulnerability detection. However, this method requires manual analysis in advance and it needs to traverse all the possible execution paths to find out the vulnerable ones. The deeper the path goes, the more time it costs to detect the contracts. This paper proposes an approach to detect smart contracts vulnerability on blockchain by using machine learning(ML) methods. This approach aims to build a general benchmark for new vulnerability detection in order to reduce the demand of expert manpower. Moreover, the high-speed-performance ML algorithm makes quick detection comes true. As long as we adjust the threshold of the model, it can work as a fast prefilter for the traditional symbolic analysis tools in further improvement of accuracy.
Design of storage and management device of packaged FBG sensors based on RFID
Authors: Liu Shuochao , Lin Zhecong , Lu Meng , Zhu Pingyu
Published: March 2021

In the application of fiber Bragg grating(FBG) sensor in structural condition monitoring, the reasonable layout scheme is designed according to its central wavelength. However, the paper label with FBG central wavelength information may be lost when FBG is used, therefore it is difficult to store and manage FBG sensors. This paper designs a storage device and its management system of packaged independent FBG sensor based on RFID technology. The oblique grid structure can store the FBG sensors with the same central wavelength. The RFID reader module is arranged on the top of the box-type device with multi-layer oblique grid. The packaged FBG sensors are stored, read and classified with the help of special software.
Simultaneous Localization and Mapping using differential drive mobile robot under ROS
Authors: Housein Alaa Aldeen , Xingyu Gao
Published: March 2021

The present work shows implementation of SLAM for mapping and navigation in indoor environment under robot operating system ROS, using differential drive robot provided by laser scan. Mapping process is done by using ROS packages based on extended kalman EKF filter algorithm, whereas localization is done by using packages based on adaptive Monte Carlo localization AMCL, navigation is performed by ROS built functions. Paper also will give concrete intuition about using EKF to accomplish SLAM, and shows how the results diverge in case of not using SALM algorithm.
Design and dynamic simulation of manipulator
Authors: Sun Mingming , Zhao Yanan , Wang Zhonghui , Liang Bing , Shao LiuBao
Published: March 2021

Using a portable manipulator to take out the recovery crucible from the rare earth redox bath, its reliability is one of the bottlenecks restricting production automation. According to the production process of praseodymium and neodymium alloy, determine the mechanism design, and analyze the force to determine the motor selection. The manipulator model is established in the SolidWorks environment, the communication interface is compatible, and the adams software is imported to conduct dynamic simulation analysis of the manipulator mechanism. The manipulator opens and closes smoothly, and the output clamping force meets the theoretical value requirements. The motor is selected to meet the requirements of use.
A Novel Method for Knot-Tying in Autonomous Robotic assisted Surgery Using Deep Learning
Authors: Zhou Zhenning , Zu Xueying , Cao Qixin , Zhu Xiaoxiao
Published: March 2021

With the advent of robot-assisted surgery, surgical task automation, which means that robotic assistants could autonomously execute certain commonly occurring tasks, is more and more appealing and has been studied over the last several years because of the booming of deep learning. Mainly, such partial automation can help reduce the surgeon’s workload and allow surgeons to focus more on critical elements of the surgical workflow. In this paper, we propose a novel method using deep learning based on Variational Autoencoders for robotic assistants to learn knot-tying with the Data Set of manual operation, instead of learning from video demonstrations. Taking the circle action of knot-tying as an example, we make use of the VAE network to conduct feature learning and autonomous generation of knot-tying trajectories. During this time, the appropriate VAE network is built and implemented training, and after 100 rounds of training, experimental results show that we successfully acquire trajectories as expected using smaller Data Set with VAE network.
Design and Realization of full-automatic Device for Needle Pressure Gauge Verification
Authors: Su Yiming , Zhang Qi , Yang Shuiwang , Liu Yulei
Published: March 2021

In order to realize the full-automatic verification of needle pressure gauges of various specifications, a full-automatic verification device of pressure gauges based on six axis cooperative manipulator is designed. On the basis of reading the value of pressure gauges based on machine vision in the early stage, the device adds the structure of automatic grabbing, automatic installation and automatic calibration, so as to realize the loading, tightening, pressurizing, reading and unloading of pressure gauges in the verification process Automatic operation of material and data processing.
Research on nonlinear dynamic model of spur gear pair
Authors: Zhang Chen , Liu Xuew , Shi Xingl , Ling Xiaom
Published: March 2021

In this study, the meshing dynamic model of spur gear is established. Firstly, the relationship between center distance variation caused by geometric eccentricity, assembly error and shaft bending deformation and gear meshing parameters such as pressure angle, backlash and meshing stiffness is established. Secondly, under the dynamic condition, the dynamic model of the gear pair is established by calculating the backlash and meshing stiffness. Finally, a 6-DOF dynamic model including geometric eccentricity and pressure angle is generated. The numerical results show that the dynamic responses predicted by different models are significantly different. There is a significant coupling effect between gear meshing parameters and dynamic response. In a large range of torque and speed, there are differences between the meshing forces, especially in the main resonance speed and 1/3 of the speed.
Nonlinear vibration mechanism of elastic beam in large overall rotation with rotor eccentricity effect
Authors: Zhao Lei , Yan Zhao-Fang , Zhao Xin-Hua , Li Bin
Published: March 2021

The eccentric effect of rotor has seriously affected on the stability and precision of the mechanism at high speed for light and flexible mechanism in industrial application. The analysis of nonlinear vibration mechanism must be completed to realize precision and stable control of elastic beam in a large overall rotation. Firstly, the slender flexible rod is assumed as Euler-Bernoulli beam. We apply the deformation theory of elastic beam to establish its kinematic constraint relationship. Its dynamic model is built with Galerkin method and Hamilton principle. Then the Lagrange method is used to establish the rotor dynamics model based on the Jeffcott rotor. The coupling part between the motor and the elastic beam is assumed to be rigidly connected, and the dynamic model of the motor-elastic beam system can be obtained. Lastly, we analyze the nonlinear vibration mechanism of the elastic beam with rotor eccentricity effect through applying the fourth-order Runge-Kutta method and the superposition principle of traveling wave. It provides an important theoretical basis for making an effective vibration suppression strategy for elastic beam.
Design of mobile and low-cost feeding device for aquaculture feeds
Authors: Mao Wenwu , Zhang Kexin , Wang Dengkui , Lin Mindong , Chen Jiafeng
Published: March 2021

Artificial feeding is still widely used by small and medium-sized farmers in aquaculture, which requires a large labor cost and cannot guarantee the feeding efficiency. A mobile, low-cost, simple and practical feeding device for aquaculture feed was designed, including the overall scheme, the design of silo, feeding bucket, feeding mechanism and other mechanical structures. The feeding device can reduce the cost of aquaculture and improve the feeding efficiency.
Research on Key Technology of Water Robot Avoiding Collision Based on Improved VFH Algorithm
Authors: Chen Zihao , Pan Baofeng
Published: March 2021

For water robots in the intelligent operations meet to collision problems, a key collision avoidance algorithm based on VFH is developed, and the algorithm is improved and optimized, with a laser radar to launch the electromagnetic wave at a certain period Finally water robot controller was used to deal with data so as to analyze and process the data. Based on this, the histogram of obstacle vector field is established to judge the feasible and infeasible regions of the robot on water. Compared with the direction of the target destinations in feasible region corresponding weighting function is designed so as to determine the feasible area with smaller weight. the simulation by MATLAB to water robot position point for data analysis, Thus the simulation of water robot collision avoidance path diagram.
Summary of fatigue durability analysis of whole vehicle
Authors: Shen Nai-Rui , Liu Fei , Qu Jing-Jing , Lan Hai , Liao Hong-Yi , Zou Yu-Jie , Su Qi
Published: March 2021

Technical characteristics and development trend of the fatigue durability analysis of the whole vehicle were reviewed in the directions. These existing research results were systematically summarized from the research status, signal acquisition, finite element analysis, load spectrum extraction and fatigue life. Wherein, the strengths and weaknesses of the virtual iteration technology was explained in detail, in which the result evaluation standard was mainly composed of relative damage value; and also the characteristics of fatigue damage theory and analysis method were summarized detailedly; additionally, the practical critical plane method possessed the advantages of the measurable component damage values, but this method still needed to be solved the problems of crack propagation direction. Moreover, according to the existing technology and achievements, reducing model errors and road conditions selection will become the development trends of vehicle fatigue durability technology in the future.
Experimental study on static/dynamic performance of escalator steps
Authors: Liang Xiao , Ren Facai , Gan Bin , Hou Shaoyi , Shi Hongjun
Published: March 2021

The step performance is very important for the safe operation of escalator. In this paper, static and dynamic load tests of aluminum alloy and stainless steel escalator steps are carried out. The breaking strength, deformation and first order modal frequency of the step with different sizes and materials are analyzed. The results show that the breaking strength and first order modal frequency of aluminum alloy step are higher than those of stainless steel step, and the maximum deformation of aluminum alloy step is smaller than that of stainless steel step.
Based on workbench simulation to research the influence of different pin structures on the assembly of silicone rubber buttons and PCB
Authors: Tang Changhua , Ma Xiaosong , Wu Keye , Ming Zihao
Published: March 2021

At present, one silicone rubber button and no pins nozzle structure that can be used for automatic sticking group have been developed, but the pin’s structure of the silicone button greatly affects the success rate of the sticking group and the stability after the sticking group is completed. Therefore, it is very important to research the assembly process of silicone rubber buttons with different pin structures and PCB, which has great research significance. In this paper, we used Solidworks to create three silicone rubber buttons with conical, arc, and cylindrical node pin structures respectively, used workbench to simulate the process of button pins and PCB assembly. By comparing the pressure changes of different pin structures in the process of fitting and analyzing the influence of different pin structures on the assembly process. It is concluded that the arc node pin structure is more effective.
The modular structure designs of a type of stir frying device
Authors: Lv Zhongliang , Li Zelun , Zhou Chuande , Yang Lin , yang Yi , Wang Binbin , Zhu Ruixiang , Han Yu , Han Senping , Huang Zhicheng
Published: March 2021

The main task of cooking robot is to complete all kinds of cooking work instead of people. Based on the single-chip microcomputer control system, the author describes the modular design of a stir frying device in this article, and elaborates on the overall scheme design, mechanical structure design and control system design of a type of stir frying device. The device detects the temperature in the pot through a temperature sensor, controls the mechanical arm, the pancake turner and ingredient tray through two steering engines, a stepping motor and an adjustable-speed DC motor to make them reach the designated position. The entire cooking process is coordinated and controlled by the program. It can complete a series of actions such as pouring oil, putting vegetables in the pot, adding seasonings, stir-frying. Besides, it also can control the cooking time and heating degree in each link until the production of a dish is completed. The stir frying device realizes the modularization and automation of the cooking process.