Small Arc Research Articles

The Forming Parameters Study Based on ITER Prototypical Vertical Stability Coil Small Bending Arcs

The vertical stability (VS) coil is a set of circle-shaped multilayer in-vessel coil that is arranged in the vacuum vessel. For International Thermonuclear Experimental Reactor (ITER) prototypical VS coil, to avoid the interference with other in-vessel components some small bending arcs are designed. They are the R600 S-shaped bending arc with the angle of 9.2°, the R600 W-shaped bending arc with the angle of 20.3°, 38.1°, 20.3°, and the R215 S-shaped bending arc with the angle of 53.6°. The forming parameters of these arcs are studied in the article. Given the fact of conductor rebound after bending, the key issues of forming the arcs are to determine the suitable wheel mold radius and rotation angle. With regard to the determination of wheel mold radius, the forming deformation states of conductor under different wheel mold radius are simulated. Then the conductor displacement data after rebound are extracted to acquire the conductor inner and outer arcs fitting equations and the corresponding conductor radii are obtained simultaneously. If the calculated conductor central radius is different with the target value, the wheel mold radius will be adjusted and new simulation is employed. The reiteration work is terminated until the target radius is obtained. Subsequently, the wheel mold radius obtained in the data fitting process is referenced to fabricate the matching wheel mold. And the forming experiment is launched to verify the feasibility of conductor bending based on the above wheel mold radius. As to the determination of wheel mold rotation angle, the bending simulation and data fitting are carried out first. Then the process is repeated continuously until the target bending angle is obtained. Finally, the obtained wheel mold rotation angle is assigned as the preliminary bending angle in the forming experiment. If the forming results fail to satisfy the angle requirement, the preliminary bending angle is adjusted slightly and the forming experiment is performed again until the target bending angle is achieved. In addition, wrinkles are found during the forming process for the R215 S-shaped arc. To deal with the wrinkle issue a series of forming technology are attempted, while nearly all of them seem to be not feasible. Finally, bushing is installed at the outer surface of conductor jacket to reinforce its strength and resist the buckling impact from magnesium oxide (MgO). The forming experiments indicate bushing technology successfully eliminates the large wrinkles on the jacket.

Electromagnetic Stirring in an Electric Arc Metal Melt

The necessity of studying the stirring of liquid-metal components to form homogeneous alloys is substantiated. A mathematical model is developed for the electromagnetic stirring of alloys produced in an electric arc furnace. A special-purpose experiment is carried out to test the proposed model. The results of calculations and experiments performed on a small electric arc furnace are presented. Good agreement of the proposed theory with the experimental results is reached, and recommendations are given for improving the existing technological equipment.

Mindset matters: how mindset affects the ability of staff to anticipate and adapt to Artificial Intelligence (AI) future scenarios in organisational settings.

Any first step in organisational adaptation starts with individuals’ responses and willingness (or otherwise) to change an aspect of themselves given the transcontextual settings in which they are operating (Bateson in Small arcs of larger circles: framing through other patterns, Triarchy Press, Axminster, 2018). This research explores the implications for organisational adaptation strategies when Artificial Intelligence (AI) is being embedded into the ecology of the organisation, and when employees have a dominant fixed or growth mindset (Dweck in Mindset: changing the way you think to fulfil your potential. Robinson, London, 2017). Research participants were supplied with a single scenario based in 2030, where—as a result of Artificial Intelligence technology implementation—employees were going to be displaced. Using Torbert’s (Organizational wisdom and executive courage, New Lexington Press, San Francisco, 1998) ‘first, second and third person’ research theory, participants were asked to independently review their thoughts, sense, and image of the future from a fixed mindset position (considered to be the worst case), then from a growth mindset perspective (best case), and then do the same collectively. Five key findings are outlined which support the principle that having a growth mindset is a key component of adaptive capacity and futures literacy. The five key findings conclude that AI adaptation processes need to include compassion and authenticity, embodiment, fundamental needs and motivations, mutual learning and considering what lies beyond the edges of the organisation (Bateson in Small arcs of larger circles: framing through other patterns, Triarchy Press, Axminster, 2018).

Modelling of the thermal state and the melting loss of a graphite electrode in the conditions of the evaporative cooling in the arc furnace

The cost of the graphite electrodes amounts greater proportion in the final value of the finished product. This calls for finding opportunities to reduce the maintenance costs of AC and DC furnaces used in foundries. The aim of the study is the creation of a mathematical model and the analysis of the efficiency of the evaporative cooling method in reducing the amount of the graphite electrodes used in small capacity arc furnaces. The mathematical model and the computer program allow determining the thermal state of the electrode and the melting loss of the graphite, the model is developed for a primarily cylindrical electrode and takes into account: the current passing through an electrode, the time of the electrode being in the electrified furnace, and the parameters of the water evaporative cooling. The paper presents the received data about the melting loss of the graphite per ton of steel against the water consumption during the evaporative cooling. The graphite consumption in the arc furnaces of 10–12 tons’ capacity is reduced by 40 %. The recommended water consumption for the evaporative cooling of electrodes for all types of foundry furnaces is 0.1–0.2 m3/h.

Early Clinical Outcomes and Dosimetric Evaluation in Post Mastectomy Radiotherapy in Locally Advanced Breast Cancer: A Phase II Open Label Randomized Study between 3DCRT and VMAT

Post mastectomy Radiation (PMRT) is indicated as adjuvant treatment in the multimodality management of Locally Advanced Breast Cancer (LABC). Three-Dimensional Conformal Radiation (3DCRT) for PMRT is used with tangential fields for better target coverage and sparing of organs at risk (OAR). In comparison, VMAT has the potential to improve the coverage and decrease the OAR doses. We prospectively conducted a phase II randomized study comparing 3DCRT (Arm A) and VMAT (Arm B) in PMRT with regional nodal irradiation (RNI) to evaluate dosimetric and clinical differences between the two modalities. Women aged ≥ 18 years with locally advanced breast cancer undergoing MRM were recruited in the study. Forty patients were accrued after Institutional Ethics Committee approval. Contouring was done as per the standard RTOG guidelines. For 3DCRT, Planning was done with single isocenter technique. Two tangential fields with field in field were used for PTV-CW and AP-PA fields with higher AP weightage were used to cover PTV-RNI. For VMAT, two small partial arcs were used. The dose prescribed was 50 Gy in 25 fractions over 5 weeks. Contouring and planning was done on MONACO treatment planning system. Dosimetric analysis was done and compared between the arms. Clinical acute toxicity, late toxicity was noted with RTOG acute toxicity criteria. Quality of life (QOL) was assessed with EORTC BR 23 questionnaire. Statistical analysis was done with SPSS v 21 with chi square test and p-value < 0.05 was considered as significant. Between Jan 2018 to March 2019, forty patients were accrued in the study and twenty patients were randomized to each arm. All patients received planned allocated treatment and were eligible for analysis. PTV CW coverage was similar in both the arms. PTV RNI V95 coverage were better in VMAT arm (97.8%) than 3DCRT arm (94.5%) (p = <0.001). The ipsilateral lung V5 and V20 was 51.6% and 24.7% for VMAT and 47.1% and 27.8% for 3DCRT (p = 0.0185 and p = 0.167). The thyroid V45 was 51.3% for 3DCRT and 42% for VMAT arm (p = 0.018)]. The heart Dmean for 3DCRT and VMAT was 4.3Gy and 6.5Gy (p = 0.0372). There was no significant difference in skin, subcutaneous, lymphedema or lung toxicity between the two arms at 1, 3, and 6 months. There was no difference in global health status and QOL between two arms at 1, 3, and 6 months. No loco-regional recurrence was noted at 6 months. VMAT provides better coverage to lymph nodes with potential to decrease ipsilateral lung dose. The clinical acute toxicity, late toxicity and QOL was similar with VMAT and 3DCRT. A large prospective trial and longer follow-up is needed to confirm the findings.

Folding and Bending Planar Coils for Highly Precise Soft Angle Sensing

AbstractSensors detecting angles created by deformable structures play an increasing role in soft robotics and wearable systems. However, the typical sensing method based on strain measurement strongly depends on the viscoelastic behaviors of soft substrates and on the location of sensors that affect the sensing reliability. In this work, the changes in magnetic field coupling produced in space by planar coil deformation are investigated, for implementing a new direct transduction strategy, the soft inductive angle sensing (SIAS). A numerical analysis tool is developed for rigorously studying the inductance variations resulting from planar coils’ bending, folding, and folding with a small arc. Copper or liquid metal coils, having different shapes, pitches, and sizes are built and characterized. Results show that the SIAS is hysteresis‐free, velocity‐independent, highly sensitive, ultrastable, and with fast response, guaranteeing highly precise (0.1° incremental folding angle change) and reliable measurements. It is insensitive to coil materials and to behavior of embedding soft materials, and scalable (across 10 times scale). The SIAS is adopted in three case studies (a self‐sensing origami, a sensorized soft pneumatic actuator, and a wearable sensor) to highlight its low implementation complexity, high‐performance, and versatility, providing some insights on the enormous potential of this mechanism.

An Exact, Generalized Laplace Resonance in the HR 8799 Planetary System

Abstract A system of four super-Jupiter planets around HR 8799 is the first multiplanet configuration discovered via the direct imaging technique. Despite over a decade of research, the system’s architecture is still not fully resolved. The main difficulty comes from a still narrow observing window of ∼20 yr that covers small arcs of orbits with periods from roughly 50 to 500 yr. Soon after the discovery, it became clear that unconstrained best-fitting astrometric configurations self-disrupt rapidly due to strong mutual gravitational interactions between the companions of ≃10 Jupiter mass. Recently, we showed that the HR 8799 system may be long-term stable when locked in a generalized Laplace 8:4:2:1 mean-motion resonance (MMR) chain, and we constrained its orbits through the planetary migration. Here we qualitatively improve this approach by considering the MMR in terms of an exactly periodic configuration. This assumption enables us to construct for the first time the self-consistent N-body model of the long-term stable orbital architecture using only available astrometric positions of the planets relative to the star. We independently determine the planetary masses, which are consistent with thermodynamic evolution, and the parallax overlapping to 1σ with the most recent Gaia DR2 value. We also determine the global structure of the inner and outer debris disks in the [8, 600] au range, consistent with the updated orbital solution.

Using natural viewing behavior to screen for and reconstruct visual field defects.

There is a need for simple and effective ways to screen for visual field defects (VFD). Watching a movie is a simple task most humans are familiar with. Therefore we assessed whether it is possible to detect and reconstruct visual field defects based on free viewing eye movements, recorded while watching movie clips. Participants watched 90 movie clips of one minute, with and without simulated visual field defects (sVFD), while their eye movements were tracked. We simulated homonymous hemianopia (HH) (left and right sided) and glaucoma (small nasal arc, large nasal arc, and tunnel vision). We generated fixation density maps of the visual field and trained a linear support vector machine to predict the viewing conditions of each trial of each participant based on these maps. To reconstruct the visual field defect, we computed “viewing priority” maps and maps of differences in fixation density of the visual field of each participant. We were able to classify the simulated visual field condition with more than 85% accuracy. In simulated HH, the viewing priority distribution over the visual field indicated the location of the sVFD in the simulated HH condition. In simulated glaucoma the difference in fixation density to the control condition indicated the location of the sVFD. It is feasible to use natural viewing behavior to screen for and reconstruct (simulated) visual field defects. Movie clip viewing in combination with eye tracking may thus provide an alternative to or supplement standard automated perimetry, in particular in patients who cannot perform the latter technique.

A Small Intervals Theorem for Subharmonic Functions

Let \(\mathbb{C}\) be the complex plane, E be a measurable subset of a segment \([0, R]\) of the positive semiaxis \(\mathbb{R}^+\), and \(u\not\equiv - \infty\) be a subharmonic function on \(\mathbb{C}\). The main result of this article is an upper estimate of the integral of the module \(|u|\) over a subset of E through the maximum of the function u on a circle of radius R centered at zero and the linear Lebesgue measure of subset E. Our result develops one of the classical theorems of R. Nevanlinna, established in the case of \(E=[0, R]\), and versions of so-called small arcs lemma by Edrei–Fuchs for small intervals on \(\mathbb{R}^+\) from the works of A.F. Grishin, M.L. Sodin, and T.I. Malyutina. Our estimate is uniform in the sense that the constants in the inequality are absolute and do not depend on the subharmonic function u, under the semi-normalization \(u(0)\geq 0\).

Design and characteristics of a triple-cathode cascade plasma torch for spheroidization of metallic powders

Arc plasma torch is an effective tool for spheroidization of metallic powders. However, as most conventional plasma torches were not specifically designed for plasma spheroidization, they may exhibit the disadvantages of the radial injection of powders, large fluctuations in the arc voltage, large gas flow rate, and disequilibrium between multiple plasma jets during the spheroidization process. Therefore, this paper presents a triple-cathode cascade plasma torch (TCCPT) for plasma spheroidization. Its structural design, including three cathodes, a common anode, and three sets of inter-electrodes, are detailed to ensure that powders can be inserted into the plasma jet by axial injection, the arc voltage fluctuations are easily maintained at a low level, and the plasma torches can work at a relatively small gas flow rate. Experimental results showed that the proposed TCCPT exhibits the following characteristics: (1) a relatively small arc voltage fluctuation within 5.3%; (2) a relatively high arc voltage of 75 V and low gas flow rate range of 10–30 SLM; (3) easy to be maintained at the equilibrium state with the equilibrium index of the three plasma jets within 3.5 V. Furthermore, plasma spheroidization experiments of SUS304 stainless steel powers were carried out using the proposed TCCPT. Results verified that the proposed TCCPT is applicable and effective for the spheroidization of metallic powders with wide size distribution.

Mean first passage time for a particle diffusing on a disk with two absorbing traps at the boundary.

The problem of survival of a Brownian particle diffusing on a disk with a reflective boundary that has two absorbing arcs is treated analytically. The framework of boundary homogenization is applied to calculate the effective trapping rate of the disk boundary, and this enables estimation of the mean first passage time. The method of conformal mapping is applied to transform the original system to a simpler geometrical configuration (a flat reflective boundary with a periodic configuration of identical absorbing strips) for which the analytical solution is known. The expression for the mean first passage time is simplified for some limiting cases (small arc or small gap). The derived analytical expressions compare favorably with the results of Brownian particle simulations and other analytical results from the literature.

The Combination of Small Group Discussion and ARCS (MODis-ARCS Strategy) to Improve Students’ Verbal Communication Skill And Learning Outcomes

This study aimed at discovering the implementation of MODis-ARCS strategy to students’ verbal communication skill and learning outcomes. This study was a quasi-experimental using non- equivalent control group design. Purposive sampling was used to collect the data. There were 65 students of information technology education (control) and physics education (experimental) who used as the samples of study. The MODis-ARCS strategy was implemented on the experimental group, while small group discussion was used in the control group. Data collection techniques used test instrument that was in the form of essay items and non-test which was in the form of observation sheets of communication skill. Validity scores, Cronbach’s coefficient alpha, n-gain, independent sample t-test and paired t-test were used as the data analysis techniques. The results of study indicated that 1) n-gain of students’ learning outcomes and verbal communication skill for the control group was 0.12 and 0.07, in which it was categorized as low, while for the experimental group was 0.29 and 0.48 in the moderate category. 2) Both of groups had similar initial abilities, and there was a difference on the learning outcomes, as well as the verbal communication skill between the control and experimental classes, 3) There was an improvement on the students’ learning outcomes and verbal communication skill on the control and experimental groups, in which the significance value was ɑ=5%; however, the improvement of experimental group was greater than the control group. Therefore, it can be concluded that the MODis-ARCS strategy can improve the students’ verbal communication skill and learning outcomes.

Design improvement of flapping hydrokinetic turbines

This investigation deals with the flow control and the enhancement of the output power of a flapping foil turbine. The connected gurney flap (GF) is a small arc that oscillates with a given pitching angle. The incompressible laminar flow around a simple flat plate equipped with an oscillating gurney flap is solved using a computational method. A user-defined function and a coupled layering/sliding dynamic mesh technique available in ANSYS FLUENT.15 are used to adjust both the blade and the flap positions during the turbine flapping cycle. It was shown that an appropriate synchronization between the flap oscillation and the turbine blade rotation could modify the blade flap camber, which corrects, in turn, the pressure distribution and therefore boosts the lift force during both the up-stroke and down-stroke stages. The application of this strategy of control enhances the output power dramatically compared with a clean flapping turbine blade.

Numerical investigation of the fatigue performance of elastic rail clips considering rail corrugation and dynamic axle load

To analyze the reasons for rail clip fracture, the characteristics of rail corrugation were first measured using a rail corrugation meter. The vibration acceleration of the fastener clips at the sections with/without rail corrugation was measured, and the effects of rail corrugation on the clip vibration were analyzed. After this, a vehicle--track coupling dynamic model and a refined model for the fastener system were established in order to study the effects of rail corrugation on the vibration acceleration and stress on critical points. Finally, the rail grinding limits were determined based on the fatigue analysis method and the damage accumulation theory from the aspect of the fatigue life of the clip. The results of the study showed that the main wavelength of rail corrugation at the rail clip fracture section was approximately 40 mm. The vibration acceleration of the clip caused by rail corrugation was too large. Under normal installation conditions, the maximum clip stress was 1490 MPa at the small circular arc on the rear arch, which was identical to the on-site fracture location. The intrinsic frequency of the clip was approximately 810 Hz. Rail corrugation excited and triggered the forced vibration of the clip, and induced resonance at a speed of 120 km/h and a wavelength of 40 mm. The large cyclic stress amplitude of the clip with rail corrugation increased from 44 MPa to 68 MPa when compared with the clip without rail corrugation. Rail clip fracture was caused by the naturally occurring resonance fatigue arising from rail corrugation. For metro lines designed with a maximum speed of 120 km/h, it was suggested to control the rail corrugation amplitudes with a wavelength of 40 mm, 50 mm, 30 mm, 120 mm and 160 mm to below 0.04, 0.08, 0.16, 0.19 and 0.2 mm, respectively, taking into account the fatigue life of the clip.

The monotonicity method for the inverse crack scattering problem

The monotonicity method for the inverse acoustic scattering problem is to understand the inclusion relation between an unknown object and artificial one by comparing the far field operator with the artificial operator. This paper introduces the development of this method to the inverse crack scattering problem. Our aim is to give the following two indicators: One (Theorem 1.1) is to determine whether an artificial small arc is contained in the unknown arc. The other one (Theorem 1.2) is whether an artificial large domain contains the unknown one. Finally, numerical examples based on Theorem 1.1 are given.

Calculation and analysis of the arcs efficiency of small and large capacity arc steel-melting furnaces

In the course of the research, the calculation and performed analysis of the arc efficiency of furnaces ASF-5 and ASF-100 power furnaces were performed and the average arc efficiency for melting was determined. The reasons of the increased specific consumption of electric power on charge melting by arc steel-melting furnaces of small capacity in comparison with heavy-load furnaces are revealed. Efficiency of arcs of low-tonnage furnaces is much less than the same indicator of modern heavy-duty arc steel-melting furnaces (ASF). Low efficiency of arcs of light-duty furnaces leads to a significant specific power consumption for smelting, comprising 700-750 kWh/t, that is 1.9-2 times higher than the specific energy consumption in modern furnaces ASF-120, amounting to 375 kWh/t. With the use of devices for foaming slag in furnaces ASF-5 the average melting efficiency of furnaces can be increased, and the specific electricity consumption for melting will be reduced to 440-480 kWh/t.

Одна теорема о малых интервалах для субгармонических функций

Let $\mathbb C$ be the complex plane, $E$ be a measurable subset in a segment $[0, R]$ of the positive semiaxis $\mathbb R^+$, $u\not\equiv -\infty$ be a subharmonic function on $\mathbb C$. The main result of this article is an upper estimate of the integral of the module $|u|$ over a subset of $E$ through the maximum of the function $u$ on a circle of radius $R$ centered at zero and a linear Lebesgue measure of subset $E$. Our result develops one of the classical theorems of R. Nevanlinna in the case of $E=[0, R]$ and versions of so-called Small Arcs Lemma by Edrei-Fuchs for small intervals on $\mathbb R^+$ from the works of A.F. Grishin, M.L. Sodin, T.I. Malyutina. Our obtained estimate is uniform in the sense that the constants in the estimates are absolute and do not depend on the subharmonic function under the semi-normalization $u(0)\geq 0$.

Super-fine stainless wires enabled multifunctional and smart reactive powder concrete

Super-fine stainless wire (SSW) with excellent mechanical, electrical, thermal and electromagnetic characteristics can form a widely-distributed reinforcing network in reactive powder concrete (RPC) at low dosage, thus endowing RPC with desired mechanical performance and functional property. The multi-functional and smart properties of SSW reinforced RPC were investigated in this paper. The research results indicated that the flexural strength, compressive strength and flexural toughness of RPC reinforced with 1.5% SSWs are 31.9%, 41.2% and 114.4% higher than that of RPC without SSW. The electrical resistivity of composites is reduced by six orders of magnitude and the electrochemical impedance spectroscopy only shows small flat arcs in the first quadrant. SSW reinforced RPC exhibits stable piezoresistive response under cyclic compressive loading. Meanwhile, the gauge factor of 1.5% SSWs reinforced RPC under monotonic compressive loading can reach 153.9. The addition of 1.5% SSWs leads to 19.9% increase in damping ratio of RPC as well as 202.9% increase for electromagnetic wave shielding efficiency at the frequency of 4 GHz. The electromagnetic wave absorbing property of RPC reinforced with 1.5% SSWs exceeds 125.0% of that of RPC without SSW in the frequency range of 17–18 GHz. The addition of SSW can effectively increase the thermal conductivity and wear resistance of RPC. SSW reinforced RPC has great potential for developing multi-functional and smart infrastructures, thus improving their safety, longevity and function.

Nature of a shell of young stars in the outskirts of the Small Magellanic Cloud

Context. Understanding the evolutionary history of the Magellanic Clouds requires an in-depth exploration and characterization of the stellar content in their outer regions, which ultimately are key to tracing the epochs and nature of past interactions. Aims. We present new deep images of a shell-like overdensity of stars in the outskirts of the Small Magellanic Cloud (SMC). The shell, also detected in photographic plates dating back to the fifties, is located at ∼1.9° from the center of the SMC in the north-east direction. Methods. The structure and stellar content of this feature were studied with multiband, optical data from the Survey of the MAgellanic Stellar History (SMASH) carried out with the Dark Energy Camera on the Blanco Telescope at Cerro Tololo Inter-American Observatory. We also investigate the kinematic of the stars in the shell using the Gaia Data Release 2. Results. The shell is composed of a young population with an age ∼150 Myr, with no contribution from an old population. Thus, it is hard to explain its origin as the remnant of a tidally disrupted stellar system. The spatial distribution of the young main-sequence stars shows a rich sub-structure, with a spiral arm-like feature emanating from the main shell and a separated small arc of young stars close to the globular cluster NGC 362. We find that the absolute g-band magnitude of the shell is Mg, shell = −10.78 ± 0.02, with a surface brightness of μg, shell = 25.81 ± 0.01 mag arcsec−2. Conclusion. We have not found any evidence that this feature is of tidal origin or a bright part of a spiral arm-like structure. Instead, we suggest that the shell formed in a recent star formation event, likely triggered by an interaction with the Large Magellanic Cloud and or the Milky Way, ∼150 Myr ago.

Evaluation of different planning methods of 3DCRT, IMRT, and RapidArc for localized prostate cancer patients: planning and dosimetric study

BackgroundDifferent planning methods of IMRT planning techniques (IMRT (DMLC) and RapidArc) vs. stander techniques (three-dimensional radiation therapy (3DCRT)) will be evaluated for prostate cancer patients’ planning and verification. Three groups of localized prostate cancer patients are planned and evaluated regarding DVHs and practical radiation dosimetry, and ten 3DCRT plans are assessed statistically for each patient.ResultsPlan (7) with parameters of five equally weighted fields with angles of 0°, 45°, 90°, 270°, and 315° and energy of 15MV is the most suitable plan both for PTV coverage and for OAR sparing with a fewer number of fields and fewer number of gantry angles. IMRT complexity involves the requirement of long treatment times and additional effort for planning, safety checks, and quality control before the patient start the treatment and proceed.ConclusionsThe selected plan also is more safe on patients up to 7400 cGy than other plans and is easier to be applied compared to IMRT and RapidArc plans, depending on patient geometry. IMRT radiation doses are more effective and can safely be delivered to PTV with little side effects compared with 3D conformal and conventional techniques. RapidArc has the advantage of re-optimizing and small arcs of variable parameters in dose delivery, taking into account the maximum speed of gantry and MLCs.