Accelerator Concepts Research Articles

The influence of Prior Knowledge on Learning Scientific Terminology: A Corpus-based Cognitive Linguistic Study of acceleration in Arabic and English

The current paper expands on previous work done on the influence of learners’ language and pre-existing knowledge on understanding physics terminology by exploring the concept of ACCELERATION in Arabic and English. The study attempts to answer two questions: (1) what are the similarities and differences between the polysemy of Arabic تسارع (tasāruʿ) (acceleration) and the polysemy of English acceleration, and (2) to what extent do prototypes and factors motivating the conceptualization of تسارع (tasāruʿ) and the conceptualization of acceleration converge or diverge? To this end, Arabic and English dictionaries and corpora, the ArabiCorpus (Arabic Corpus Search Tool) and the British National Corpus (BNC), were employed. The dictionaries were surveyed to explore the various meanings of تسارع (tasāruʿ) and acceleration, while the ArabiCorpus and the BNC were employed to investigate the senses and to identify the most frequent collocates and so the prototypes of these terms. The meaning extension of the terms is examined on the basis of the cognitive mechanisms which appear in the corpora. Theoretically, the paper is informed by the prototype theory (Rosch, 1973; 1975), image schemas (Johnson, 1987), and conceptual metaphor (Lakoff & Johnson, 1980/2003). The results show that تسارع (tasāruʿ) (acceleration) and acceleration generally overlap in terms of polysemy, prototype, and images schemas as well as conceptual metaphor that organize the conceptualization of these terms. It was also found that both Arab and English speakers mix ACCELERATION up with SPEED and so misunderstand them in a scientific setting. The present findings have several implications for science curriculum design, education, and research on universal and culture-specific properties of language.

ОШИБКИ В УПРАВЛЕНИИ РОССИЙСКОЙ ЭКОНОМИКОЙ В ПЕРЕХОДНЫЙ ПЕРИОД

This article analyzes the reforms carried out by our government during the transitional period of the Russian economy, discusses various areas of this policy, as well as trends that emerged during the planned economy, and which significantly complicated the process of adjustment. The reasons for the decline in the standard of living of the population are considered. Mistakes in the management of this process were identified, which include: developing an acceleration concept that only exacerbated the crisis, an attempt to make the entire employable population of the country the owners of fixed assets, commercial banks were not exempted from taxes, a sharp reduction in military spending, and the absence of a state system for retraining employees. It is also shown how the result of these mistakes affects the Russian economy so far.

The speed of learning and learning forces

AbstractIn this paper, we propose a model of learning forces to measure and accelerate the speed of learning in knowledge initiatives. The model is built on the assertion that the speed at which companies learn and how they manage underlying learning forces determines their competitive position. Borrowing analogies from the field of physics, we introduce learning forces, learning acceleration, and knowledge value growth concepts to explain the transitions in knowledge capabilities. It is argued that these transitions can have different speeds, vectors (magnitude and direction), and trajectories (path). Further, we consider the changes in the efficiency and effectiveness of knowledge sharing to examine such transitions. The paper builds the argument that the speed and the success of learning depend on whether the vector of knowledge transition and the forces applied are aligned with the direction of the business strategy and whether or not the generated knowledge supports core capabilities (existing or potential) of the organization. Further, we examine how managing forces of friction, unlearning redundant knowledge, and creating a leaner knowledge strategy can improve learning processes.

Beyond self-acceleration: Force- and fluid-acceleration

The notion of self acceleration has been introduced as a convenient way to theoretically distinguish cosmological models in which acceleration is due to modified gravity from those in which it is due to the properties of matter or fields. In this paper we review the concept of self acceleration as given, for example, by [1], and highlight two problems. First, that it applies only to universal couplings, and second, that it is too narrow, i.e. it excludes models in which the acceleration can be shown to be induced by a genuine modification of gravity, for instance coupled dark energy with a universal coupling, the Hu-Sawicki f(R) model or, in the context of inflation, the Starobinski model. We then propose two new, more general, concepts in its place: force-acceleration and field-acceleration, which are also applicable in presence of non universal cosmologies. We illustrate their concrete application with two examples, among the modified gravity classes which are still in agreement with current data, i.e. f(R) models and coupled dark energy.

Acquisition of projectile motion concepts on phenomenon based physics’ experiential learning

This research aimed to explore the concept acquisition in phenomena based experiential learning on projectile motion. Through phenomenon based physics’ experiential learning, students analyze a phenomenon & link it with the existing concept so that it will be able to increase the acquisition of the concept. This research employed a mixed-method with an embedded experimental model. The data was obtained from test, interview, and observation on 26 tenth graders of Senior High Schools in Malang, East Java, Indonesia. Data was analyzed by N-Gain score and d-effect size. The students’ concept acquisition was grouped based on a cognitive level and projectile motion concept. The results showed that the improvement of students’ concept acquisition after taught with phenomenon-based physics’ experiential learning. The average score of pretest and posttest is 29.96 and 77.69 with high N-gain and large d-effect size, 0.681 and 5.5 respectively. Concepts of velocity and acceleration on the projectile motion should be noticed using vector analyze in daily learning.

Thickness of natural contaminant layers on metal surfaces and its effects on laser-driven ion acceleration

In the laser-driven ion acceleration studies, the naturally deposited contaminant layer on the target surface is thought to be a source of energetic ions and protons. Using ellipsometric measurements, we found that the thickness of the surface natural contaminant layer, which cannot be modified without external surface treatment, is on the order of a few nanometers. A conceptual approach is developed where “thick” and “thin” contaminant layer regimes of acceleration are identified and parameterized by the normalized thickness of the contaminant layer. These studies may also help in developing an ion acceleration concept using multilayered targets or through modifications of the target surface.

Generalized Nesterov Accelerated Conjugate Gradient Algorithm for a Compressively Sampled MR Imaging Reconstruction

To accelerate the scanning speed of magnetic resonance imaging (MRI) and improve the quality of magnetic resonance (MR) image reconstruction, a fast MRI technology based on compressed sensing is proposed. Nesterov's accelerated gradient descent (NAG) algorithm uses Nesterov acceleration to optimize the gradient descent (GD) method. However, this form of acceleration factor uses a fixed iteration curve update and can not adapt to different iteration processes. A generalized Nesterov acceleration concept is proposed. Combining the total variation model, a generalized Nesterov accelerated conjugate gradient based on total variation (GNACG_TV) algorithm is proposed. It extends the acceleration factor in a generalized manner, introducing the Frobenius norm of the objective function as a parameter, so that the acceleration factor is related not only to the number of iterations but also to the iteration process and guarantees the convergence of the iterative process. Experiments on three MR images (abdomen, head, and ankles) at different sampling ratios show that the proposed GNACG_TV algorithm compares favorably with conjugate gradient (CG), conjugate gradient based on total variation (CG_TV), Nesterov accelerated conjugate gradient based on total variation (NACG_TV), and conjugate gradient based on adaptive moment estimation (ADAMCG) algorithms in the MSE, PSNR and SSIM exhibit better performance and robustness in denoising performance for the proposed algorithm. Comparing with the result of qualitative and quantitative analysis, it was concluded that the proposed method can better reconstruct under-sampled MR images than other 4 methods. GNACG_TV can further improve the convergence speed based on Nesterov acceleration and get better reconstruction performance.

Simulation of bunched electron-beam acceleration by the cylindrical TE113 microwave field

We report a detailed simulation of a bunched electron-beam accelerated in a TE[Formula: see text] cylindrical cavity immersed in a static inhomogeneous magnetic field using a relativistic full electromagnetic particle-in-cell (PIC). This type of acceleration concept is known as Spatial AutoResonance Acceleration (SARA) in which the magnetic field profile is such that it keeps the electron-beam in the acceleration regime along their trajectories. In this work, the numerical experiments are carried out including a bunched electron-beam with the concentrations in the range [Formula: see text]–[Formula: see text][Formula: see text]cm[Formula: see text] in a TE[Formula: see text] cylindrical microwave field, at a frequency of 2.45 GHz and an amplitude of 15 kV/cm. The electron energy reaches values up to 250 keV without significant unfocusing effect that can be used as a basis to produce hard X-ray. Additionally, a comparison between the data obtained from the full electromagnetic PIC simulations and the results derived from the relativistic Newton–Lorentz equation in a single particle approximation is carried out.

Extending the concept of machine acceleration used to model the bubble-particle detachment in flotation. Part 2 – Machine acceleration of solid particles in water

The machine acceleration introduced by H. J. Schulze has been a cornerstone of the bubble-particle (BP) detachment theory. It connects the mean dissipation rate of turbulence energy of water in a flotation machine with the BP detachment. In a recent paper, we scrutinized the theory and recommended its extension to cover both the longitudinal (centrifugation) and transverse (shear) effects of water turbulence. Since there is a significant difference in the densities of water, solid particles, and air bubbles, it is unknown if the available determination of the machine acceleration using the “water particles” is a good approximation for the bubble-particle aggregates. This paper aims to provide an answer to this fundamental question. For simplicity, this paper focuses on the acceleration of solid particles in water. Specifically, we use the Basset-Boussinesq-Oseen equation to quantify the particle acceleration. The correlation method in combination with the isotropic turbulence theory is applied to predict the particle acceleration components for the full range of turbulence length scale. Comparing with Schulze’s model, our recent model shows that the particle inertia should be considered in calculating the machine acceleration, especially for large and/or heavy particles and high energy dissipation rate. Our numerical results show that the machine acceleration decreases with increasing particle size and density and increases with increasing dissipation rate of turbulent kinetic energy and turbulence intensity.

Evaluation of 2007 and 2018 Turkish Earthquake Code For the Provinces of Erzurum and Erzincan

Turkey is located on seismically very active region. Therefore, very destructive earthquakes occurred in Turkey and around, and caused loss of life and property. After the 1939 Erzincan earthquake, one of the biggest earthquakes in the instrumental period, earthquake codes were started to be prepared and these codes were updated in certain periods. Finally, "Turkey Building Seismic Code" entered into force on 01.01.2019, the earthquake hazard maps updated and new approaches in parameters calculation have been introduced. The forces affecting structures during the earthquake can be determined by static and dynamic methods. However, in order to make the calculations more practical, the spectral analysis method, which is the static method, is widely used. This method is named as design spectrum in earthquake codes. In this study, the spectral acceleration values were obtained as defined in Turkish Seismic Code 2007 (TSC 2007) and Turkish Building Seismic Code 2018 (TBSC 2018) using different soil types for Erzurum and Erzincan provinces. The location where the design spectra will be calculated is located in the first (Erzincan) and second (Erzincan) earthquake zone according to the 1996 earthquake zones map. The acceleration spectra were calculated for an earthquake with a probability of exceeding 10% probability in 50 years for the planned structure (return period 475 years, Earthquake Ground Motion Level-2). The design spectra were prepared in graphical and tabular form and the difference between them was observed. One of the biggest differences of TBSC 2018 from the old code is the abolition of the concept of earthquake zone and the introduction of the concept of direct ground acceleration. Another difference is the change of soil groups. Since these parameters are closer to reality, the calculations made with TBSC 2018 are more reliable. Keywords: Earthquake Hazard Map, Spectral Acceleration, TBSC 2018, TSC 2007 DOI: 10.7176/JSTR/5-12-07

Ground Vibration Induced by Moving Vehicle on Soft Soil

This research was conducted to gain more knowledge and investigate the ground vibration induced by vehicle at five different bridge approach location in Batu Pahat, Johor. This research also to illustrate and specify the ground vibration value based on identifying the location of an influence class of vehicle, speed of vehicle and zone of vehicle on bridge approach which are passing through to the bridge approach A (BAA) and bridge approach B (BAB). In describing vibration in the ground and in structures, the motion of the particle is utilized. This research describes the concepts of particle displacement, velocity and acceleration that are used to depict how the ground or structure reacts to excitation. This research observed the ground vibration motion, that is commonly described by identifying the peak particle velocity (PPV). Also presented, a description of the measurement technique, procedures and field data collection. From the sight of view of the result of this research, it indicated that the vibration value is more significant by all the variables. As a result, by the comparison of the variables that had been conducted with respect to the value of this vibration, it was found that the zone near the sensor shows a higher PPV value compared to the zone that is far apart from the sensor location and also vehicle class also plays a role which class IV is higher than class III and class II. The research shows potential to provide and improve the knowledge towards the importance of ground vibration from the vehicle loading by specific evaluation.

Power System Transient Stability Study by Involving Higher Order Corrections in Improved Quadratic Lyapunov Function for Singular Perturbed Model of Synchronous Generator

The assessment of transient stability of multi-machine power system, in a post-fault scenario, is a very challenging task due to highly non-linear nature of the system equations. In this work, the physical concept of maximum relative acceleration of a machine at a fault scenario is related with the boundary of stability region. This approach is extended to develop a quadratic Lyapunov function using singular perturbed modelling. Unlike the conventional energy function methods, this Lyapunov function candidate is a more general energy function and has a decaying nature around an equilibrium point. Moreover, with higher order corrections, an improved Lyapunov function candidate is presented with simulation results of power system examples. The decaying nature of Lyapunov function candidate remains similar even without higher order corrections. However, the relevance of inclusion of higher order corrections is brought out in the cases of faults occurring at other than generator buses. Also, the upper bound of singular perturbation parameter in the model is within allowable limits and ensures the accuracy of results.

Electromagnetic wave propagation in a fast pulse line ion accelerator.

The pulse line ion accelerator (PLIA) is a low-cost accelerator concept originally designed to accelerate heavy ions. Our group has been investigating the use of PLIA to accelerate light ions and believe a multi-stage PLIA could be useful for short half-life PET isotope production. The goal of this work was to develop a single prototype fast PLIA structure and demonstrate electromagnetic wave propagation using a high-voltage pulser. A 1.6m fast PLIA structure (wave speed>107 m/s) was constructed along with a high-voltage, sinusoidal pulse generator. The latter uses capacitive voltage doubling and spark gap switching. A step-up transformer couples voltage from the pulser to the PLIA coil. Voltage measurements on the coil were made in air using a high-voltage resistive probe, while capacitive probes placed along the length of the PLIA were used to measure wave propagation with the PLIA structure filled with transformer oil. Voltage measurements acquired on the primary and secondary coils of the transformer coupler in air demonstrated a peak-to-peak voltage step-up of 4.2 relative to the pulser DC charging voltage. The maximum voltage time-rate-of-change on the PLIA coil was 0.76×1013 V/s. Capacitive probe measurements indicated voltage oscillations on the PLIA coil with half-period equal to 43±0.9ns and wave speed (with oil) of 1.2×107 m/s. Average and peak accelerating gradients were conservatively estimated to be 0.44 and 0.60MV/m, respectively, with a charging voltage of 55kV. Wave propagation was demonstrated at these gradients without flashover at a vacuum pressure of 9×10-6 Torr. Submerging the pulser in oil would allow for charging voltages up to 150kV and produce accelerating gradients >1.2MV/m. Use of a multi-stage, fast PLIA for light ion acceleration could provide a low-cost complement to cyclotrons for the production of short half-life isotopes used for PET imaging, including carbon-11, nitrogen-13, oxygen-15, and fluorine-18.

Status report of the SINBAD-ARES RF photoinjector and linac commissioning

The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments, including the acceleration of ultrashort electron bunches and the testing of advanced high-gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low-charge electron beam, which is afterwards accelerated by an S-band linac section. The linac as well as a magnetic chicane will allow the production of ultrashort bunches with excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next-generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun commissioning and linac setup.

Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration

Author(s): Debus, A; Pausch, R; Huebl, A; Steiniger, K; Widera, R; Cowan, TE; Schramm, U; Bussmann, M | Abstract: Compact electron accelerators are paramount to next-generation synchrotron light sources and free-electron lasers, as well as for advanced accelerators at the TeV energy frontier. Recent progress in laser-plasma driven accelerators (LPA) has extended their electron energies to the multi-GeV range and improved beam stability for insertion devices. However, the subluminal group velocity of plasma waves limits the final electron energy that can be achieved in a single LPA accelerator stage, also known as the dephasing limit. Here, we present the first laser-plasma driven electron accelerator concept providing constant acceleration without electrons outrunning the wakefield. The laser driver is provided by an overlap region of two obliquely incident, ultrashort laser pulses with tilted pulse fronts in the line foci of two cylindrical mirrors, aligned to coincide with the trajectory of the accelerated electrons. Such a geometry of laterally coupling the laser into a plasma allows for the overlap region to move with the vacuum speed of light, while the laser fields in the plasma are continuously being replenished by the successive parts of the laser pulses. Our scheme is robust against parasitic self-injection and self-phase modulation as well as drive-laser depletion and defocusing along the accelerated electron beam. It works for a broad range of plasma densities in gas targets. This method opens the way for scaling up electron energies beyond 10 GeV, possibly towards TeV-scale electron beams, without the need for multiple laser-accelerator stages.

The Future Prospects of Muon Colliders and Neutrino Factories

The potential of muon beams for high energy physics applications is described along with the challenges of producing high quality muon beams. Two proposed approaches for delivering high intensity muon beams, a proton driver source and a positron driver source, are described and compared. The proton driver concepts are based on the studies from the Muon Accelerator Program (MAP). The MAP effort focused on a path to deliver muon-based facilities, ranging from neutrino factories to muon colliders, that could span research needs at both the intensity and energy frontiers. The Low EMittance Muon Accelerator (LEMMA) concept, which uses a positron-driven source, provides an attractive path to very high energy lepton colliders with improved particle backgrounds. The recent study of a 14-TeV muon collider in the LHC tunnel, which could leverage the existing CERN injectors and infrastructure and provide physics reach comparable to the 100[Formula: see text]TeV FCC-hh, at lower cost and with cleaner physics conditions, is also discussed. The present status of the design and R&D efforts towards each of these sources is described. A summary of important R&D required to establish a facility path for each concept is also presented.

Effect of central acceleration on the growth of a plant

In 2013, NASA conducted a series of experiments to study the growth of plants in microgravity. The interest of replicating the experiment is to study the relation of acceleration with plant growth, which is achieved by the construction of an accelerometer and the germination of different plants under certain conditions. In this paper we present the effects of different gravity values on the growth of a plant. To make the changes, the basic concepts of central acceleration (centripetal acceleration) are considered, with the help of a centrifuge any gravity value is simulated, for this, it is necessary to place the seeds at different distances from a rotation axis which is rotated continuously for several days. Two different systems were considered: a) placing the axis of rotation vertically, with this, the growth of the plants over the course of days will be observed, along with the effects on the auxins, which are responsible for geotropism, that is, the extraction of auxins from the plants placed in the centrifuge will determine the influence of rotation on the concentration of auxins; and b) the growth in the direction of gravity is affected according to the distance taken from the center of the axis of rotation. We also compare the natural growth of plants and the growth affected by the central force.

Simultaneous acceleration of two kinds of ion beams in the RISP

The Rare Isotope Science Project (RISP) is a research complex consisting of a heavy-ion accelerator, which contains a front-end system, a super-conducting linear accelerator, an isotope separator online (ISOL) system, and an in-flight system. The original purpose of the post-linear-accelerator (post-linac) section was to accelerate either a stable driver beam derived from an electron cyclotron resonance ion source, or an unstable rare-isotope beam from an ISOL system. The post-linac lattice has now been redesigned using a novel and improved acceleration concept that allows the simultaneous acceleration of both a stable driver beam and a radioisotope beam. To achieve this, the post-linac lattice is set for a mass-to-charge ratio (A/q) that is the average of the two beams. The performance of this simultaneous two-beam acceleration is here assessed using two ion beams: \(^{58}{\mathbf{Ni}}^{8+}\) and \(^{132}{} {\mathbf{Sn}}^{20+}\). A beam dynamics simulation was performed using the TRACK and TraceWin codes. The resultant beam dynamics for the new RISP post-linac lattice design are examined. We also estimate the effects of machine errors and their correction on the post-linac lattice.

A direct numerical simulation study of the influence of flame-generated vorticity on reaction-zone-surface area in weakly turbulent premixed combustion

Direct numerical simulation data obtained from two statistically stationary, one-dimensional, planar, weakly turbulent, premixed flames are analyzed in order to examine the influence of flame-generated vorticity on the surface area of the reaction zone. The two flames are associated with the flamelet combustion regime and are characterized by two significantly different density ratios σ = 7.53 and 2.5, with all other things being roughly equal. The obtained results indicate that generation of vorticity due to baroclinic torque within flamelets can impede wrinkling of the reaction surface, reduce its area, and, hence, decrease the burning rate. Thus, these results call for revisiting the widely accepted concept of combustion acceleration due to flame-generated turbulence. In particular, in the case of σ = 7.53, the local stretch rate, which quantifies the local rate of increase or decrease in the surface area, is predominantly negative in regions characterized by a large magnitude of enstrophy or a large magnitude of the baroclinic torque term in the enstrophy transport equation, with the effect being more pronounced at larger values of the mean combustion progress variable. If the density ratio is low, e.g., σ = 2.5, the baroclinic torque weakly affects the vorticity field within the mean flame brush and the aforementioned effect is not pronounced.

Plasma wakefield accelerators

Edda Gschwendtner and Patric Muggli discuss the concept of plasma wakefield acceleration and its potential for future particle colliders and other applications.