Accelerator System Research Articles

Performance Improvement of a Switched Reluctance Motor and Drive System Designed for an Electric Motorcycle

In this paper, the implementation of a switched reluctance motor (SRM) and drive system for the propulsion system of a two-seat electric motorcycle is described. The overall design focuses on the required vehicle speed, acceleration, driving distance, and overall system cost, as well as reliability. The performance of the three-phase 6/4 pole (six-stator pole and four-rotor pole) and four-phase 8/6 pole (eight-stator pole and six-rotor pole) are investigated and compared by static performance analysis and dynamic performance analysis. Their performance is further investigated by finite element analysis. The indirect torque controller in a drive system for optimal torque and efficiency operation is also mentioned. A methodology for rotor position detection and its hardware implementation are also proposed. The designed 3.5 kW three-phase 6/4 pole SRM and its drive system were constructed and tested on the test bench. A maximum efficiency of about 82% could be achieved for the SRM and drive system. It was also installed on a 120-cc electric motorcycle, and the vehicle’s performance was also validated by on-road and dynamometer testing. The maximum vehicle speed reached was 82 km/h, and a cruising distance of about 98 km at a constant speed of 40 km/h was measured.

Building a precise machine-specific time structure of the spot and energy delivery model for a cyclotron-based proton therapy system

Objective. We proposed an experimental approach to build a precise machine-specific beam delivery time (BDT) prediction and delivery sequence model for standard, volumetric, and layer repainting delivery based on a cyclotron accelerator system. Approach. Test fields and clinical treatment plans’ log files were used to experimentally derive three main beam delivery parameters that impacted BDT: energy layer switching time (ELST), spot switching time, and spot drill time. This derived machine-specific model includes standard, volumetric, and layer repainting delivery sequences. A total of 103 clinical treatment fields were used to validate the model. Main results. The study found that ELST is not stochastic in this specific machine. Instead, it is actually the data transmission time or energy selection time, whichever takes longer. The validation showed that the accuracy of each component of the BDT matches well between machine log files and the model’s prediction. The average total BDT was about (−0.74 ± 3.33)% difference compared to the actual treatment log files, which is improved from the current commercial proton therapy system’s prediction (67.22%±26.19%). Significance. An accurate BDT prediction and delivery sequence model was established for an cyclotron-based proton therapy system IBA ProteusPLUS®. Most institutions could adopt this method to build a machine-specific model for their own proton system.

Эволюция системы бизнес-акселерации предпринимательских структур в России

In conditions of economic instability, the importance of supporting entrepreneurs is increasing. The growth in the number of accelerators arouses interest in their effectiveness. Is the acceleration system capable of adapting to changing conditions? The aim is to generalize approaches to assessing changes in the acceleration system and to develop stages of its evolution in Russia. The author’s analysis of foreign and Russian publications, regulatory documents and accelerator practices was carried out using the methods of content analysis and generalization. A reasonable scientific approach is to consider accelerators as an adaptable kind of incubators. The author’s typology of the stages of acceleration evolution in Russia has been developed: 1) “Preaccelerator period” (1990s - mid-2000s); 2) “The period of primary institutionalization of accelerators” (mid-2000s - 2018); 3) “The period of building the acceleration system” (2018 to the present). It allows you to trace the process of the origin of ideas, the formation and development of the institute of accelerators. Changes in approaches to acceleration and its elements are revealed. The development strategy of the Corporation of Small and Medium-sized Enterprises indicates the emergence of a more comprehensive understanding of the acceleration system in the administrative approach. Accelerators widely represented throughout the country are able to make the greatest contribution to economic development. The transformation of the acceleration system at the municipal level carries the greatest risks of lagging behind the best federal experience. Next, empirical assessments of the contribution of accelerators to the development of the country and municipalities are required.

CNN Based Driver Drowsiness Detection System Using Emotion Analysis

The drowsiness of the driver and rash driving are the major causes of road accidents, which result in loss of valuable life, and deteriorate the safety in the road traffic. Reliable and precise driver drowsiness systems are required to prevent road accidents and to improve road traffic safety. Various driver drowsiness detection systems have been designed with different technologies which have an affinity towards the unique parameter of detecting the drowsiness of the driver. This paper proposes a novel model of multi-level distribution of detecting the driver drowsiness using the Convolution Neural Networks (CNN) followed by the emotion analysis. The emotion analysis, in this proposed model, analyzes the driver’s frame of mind which identifies the motivating factors for different driving patterns. These driving patterns were analyzed based on the acceleration system, speed of the vehicle, Revolutions per Minute (RPM), facial recognition of the driver. The facial pattern of the driver is treated with 2D Convolution Neural Network (CNN) to detect the behavior and driver’s emotion. The proposed model is implemented using OpenCV and the experimental results prove that the proposed model detects the driver’s emotion and drowsiness more effectively than the existing technologies.

Architecting a Flash-Based Storage System for Low-Cost Inference of Extreme-Scale DNNs

The size of deep neural network (DNN) models has been exploding rapidly, demanding a colossal amount of memory capacity. For example, Google has recently scaled its Switch Transformer to have a parameter size of up to 6.4 TB. However, today's HBM DRAM-based memory system for GPUs and DNN accelerators is suboptimal for these extreme-scale DNNs as it fails to provide enough capacity while its massive bandwidth is poorly utilized. Thus, we propose <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Leviathan</i> , a DNN inference accelerator, which integrates a cost-effective <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">flash-based</i> storage system, instead. We carefully architect the storage system to provide enough memory bandwidth while preventing performance drop caused by read disturbance errors. Our evaluation of Leviathan demonstrates an 8.3× throughput gain compared to the iso-FLOPS DNN accelerator with conventional SSDs and up to 19.5× higher memory cost-efficiency than the HBM-based DNN accelerator.

Historical Review of Stereotactic Radiosurgery in Juntendo University.

Juntendo University Hospital is the second hospital in Japan to start stereotactic brain irradiation using linear accelerator (LINAC) system. This report details the historical transition of stereotactic irradiation, progress of treatment technology, and change of treatment method from the beginning to the Juntendo University Hospital and Juntendo Nerima Hospital. The hospital changed the use of cobalt to the LINAC system when it was rebuilt in 1993. Total body irradiation treatment for leukemia had started around the same time. A year later, in 1994, the hospital used their LINAC systems to perform stereotactic head irradiation, otherwise known as pinpoint irradiation. In 2005, Juntendo University Nerima Hospital was opened and in September of the same year, radiation therapy using the latest model of LINAC system at that time was initiated. This was the first among all Juntendo hospitals to start intensity-modulated radiation therapy (IMRT) and image-guided radiotherapy (IGRT). In 2014, a second LINAC system for IMRT and IGRT was equipped at the Juntendo Hongo Hospital. In 2021, the LINAC systems of the Juntendo University Nerima Hospital were replaced after 15 years of usage. The new method of SRS was started using a latest LINAC systems. In this paper, I introduce the technique and progress of SRS that I have experienced mainly in Juntendo University.

ESTIMATION OF THE TOLERANCE AREA FOR CORRECTION PARAMETERS IN INDUCTION ACCELERATION SYSTEMS

he issues of formalization and numerical solution of the problems of calculating tolerances for the parameters of corrective elements for a linear induction acceleration system, which are directly related to the performance of a real object, are considered. The key moments of the dynamics of the transverse motion of particles for a specific structure of a linear induction system of acceleration are studied for given values of energy for each of the periods of the resonator. The presence of parasitic electric and magnetic fields, which arise as a result of particle displacement relative to the accelerator axis and change the transverse components of the pulses, is taken into account. The original difference model of the induction system has been transformed into a linear form. To formulate the problem statements for calculating tolerances, the scatter vectors of phase coordinates and tolerances for the correction parameters are introduced. In order to apply the methods of practical stability, the set of tolerances for the parameters of the corrective elements is given in the form of an ellipsoid. Provided that the initial displacements of the transverse coordinates relative to the axis of the accelerator are known constant values, the structured tolerance region was estimated under known linear restrictions on the spread of the phase coordinate vectors. Due to the developed algorithms of practical stability, the original problem of calculating tolerances is reduced to the problem of finding the maximum of a linear form on an ellipsoid. Some important types of restrictions on deviations of phase coordinates concerning the estimation of tolerances on the parameters of the first correction element and the number of particles are investigated. For the case of non-linear dynamic constraints on the spread of the phase coordinate vector, it is proposed to approximate the convex closed set by tangent hyperplanes. From the standpoint of practical stability, the problem of estimating tolerances for the case of given restrictions on the spread of the quality criterion is considered. With the help of practical directional stability algorithms, it is proposed to estimate the maximum tolerance ranges for parameters in terms of volume in the presence of dynamic restrictions on the spread of phase coordinates or a quality criterion.

Research on electromagnetic orbital accelerator

This paper describes the design process of the electromagnetic track accelerator system from both hardware and software aspects. It adopts three-level track acceleration and three groups of capacitors to store energy, and adds ZVS boost module to realize continuous acceleration of the electromagnetic track. The system works reliably.

Multi-node Acceleration for Large-scale GCNs

Limited by the memory capacity and compute power, singe-node graph convolutional neural network (GCN) accelerators cannot complete the execution of GCNs within a reasonable amount of time, due to the explosive size of graphs nowadays. Thus, large-scale GCNs call for a multi-node acceleration system (MultiAccSys) like TPU-Pod for large-scale neural networks. In this work, we aim to scale up single-node GCN accelerators to accelerate GCNs on large-scale graphs. We first identify the communication pattern and challenges of multi-node acceleration for GCNs on large-scale graphs. We observe that (1) coarse-grained communication patterns exist in the execution of GCNs in MultiAccSys, which introduces massive amount of redundant network transmissions and off-chip memory accesses; (2) overall, the acceleration of GCNs in MultiAccSys is bandwidth-bound and latency-tolerant. Guided by these two observations, we then propose MultiGCN, the first MultiAccSys for large-scale GCNs that trades network latency for network bandwidth. Specifically, by leveraging the network latency tolerance, we <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">first</i> propose a topology-aware multicast mechanism with a one <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">put</monospace> per <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">multicast</monospace> message-passing model to reduce transmissions and alleviate network bandwidth requirements. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Second</i> , we introduce a scatter-based round execution mechanism which cooperates with the multicast mechanism and reduces redundant off-chip memory accesses. Compared to the baseline MultiAccSys, MultiGCN achieves 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 12\times$</tex-math></inline-formula> speedup using only 28% <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 68% energy, while reducing 32% transmissions and 73% off-chip memory accesses on average. It not only achieves 2.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 8\times$</tex-math></inline-formula> speedup over the state-of-the-art multi-GPU solution, but also scales to large-scale graphs as opposed to single-node GCN accelerators.

LINAC: A Spatially Linear Accelerator for Convolutional Neural Networks

We first propose a method to utilize the spatially linear correlation between activations and weights of CNN models and accelerate the inference process via linear regression. With the proposed linear regression-based acceleration method, stronger bit-sparsity is excavated to reduce ineffectual computations during the inference in CNN acceleration systems without introducing any errors to the algorithm. We also propose the corresponding hardware accelerator based on the linear convolution mechanism: LINAC, which implements the linear convolution that exploits bit-sparsity to boost performance and energy efficiency significantly. In our experiments, LINAC boosts the inference performance by 11× on average over the present value-agnostic accelerator and outperforms other state-of-the-art bit-sparse accelerators.

Feasibility of cardiac-synchronized quantitative T1 and T2 mapping on a hybrid 1.5 Tesla magnetic resonance imaging and linear accelerator system.

Background and PurposeThe heart is important in radiotherapy either as target or organ at risk. Quantitative T1 and T2 cardiac magnetic resonance imaging (qMRI) may aid in target definition for cardiac radioablation, and imaging biomarker for cardiotoxicity assessment. Hybrid MR-linac devices could facilitate daily cardiac qMRI of the heart in radiotherapy. The aim of this work was therefore to enable cardiac-synchronized T1 and T2 mapping on a 1.5 T MR-linac and test the reproducibility of these sequences on phantoms and in vivo between the MR-linac and a diagnostic 1.5 T MRI scanner.Materials and methodsCardiac-synchronized MRI was performed on the MR-linac using a wireless peripheral pulse-oximeter unit. Diagnostically used T1 and T2 mapping sequences were acquired twice on the MR-linac and on a 1.5 T MR-simulator for a gel phantom and 5 healthy volunteers in breath-hold. Phantom T1 and T2 values were compared to gold-standard measurements and percentage errors (PE) were computed, where negative/positive PE indicate underestimations/overestimations. Manually selected regions-of-interest were used for in vivo intra/inter scanner evaluation.ResultsCardiac-synchronized T1 and T2 qMRI was enabled after successful hardware installation on the MR-linac. From the phantom experiments, the measured T1/T2 relaxation times had a maximum percentage error (PE) of −4.4%/−8.8% on the MR-simulator and a maximum PE of −3.2%/+8.6% on the MR-linac. Mean T1/T2 of the myocardium were 101234/512 ms on the MR-simulator and 103442/511 ms on the MR-linac.ConclusionsAccurate cardiac-synchronized T1 and T2 mapping is feasible on a 1.5 T MR-linac and might enable novel plan adaptation workflows and cardiotoxicity assessments.

RelSim: Computational Framework for Lifetime Reliability Assessment of Heterogeneous Accelerator Systems

RelSim: Computational Framework for Lifetime Reliability Assessment of Heterogeneous Accelerator Systems

Monte Carlo evaluation of particle interactions within the patient-dependent part of Elekta 6 MV photon beam applying IAEA phase space data.

BackgroundThis work aims to provide a simulated method to be used by designers of medical accelerators and in clinical centers to manage and minimize particles’ interaction in the patient-dependent part of a 6 MV X-Ray Beam generated by the Elekta linear accelerator system, based on the latest GATE software version 9.0 Monte Carlo simulation, IAEA phase space data, and the last version of “Slurm” computing cluster.Materials and methodsThe experimental results are obtained using the Elekta 6 MV accelerator. The simulation MC developed includes the majority of the patient-dependent segments, such as Multi-Leaf Collimator (MLC), Tongue and Groove T&G, Rounded leaf Part, including the Jaws (XY). This model is used, with a simulated Iba Blue Phantom 2 homogeneous water phantom with dimensions 480 × 480 × 410 mm3, positioned at a Source-to-Surface-Distance (SSD) of 100 cm, all of the interactions of the mega voltage 6 MV radiations in water are simulated. The IAEA phase space (PS) provided by the International Atomic Energy Agency database and cluster computing (Slurm HPC-MARWAN, CNRST, Morocco) are employed to reduce our simulation time.ResultsThe results confirm that there are many interactions in all areas and the patient-dependent part’s internal structures. Thus, electrons and positrons participation appear in the generated field previously designed to be an X-ray beam. Besides, to validate our implementation geometry, the PDD’s and transverse profiles, at a depth ranging from 1.5 to 20 cm, for a field size of 10 × 10 cm2, the beam quality such as D10%, dmax (cm), d80 (cm), TPR(20/10), the two relative differences in dose were derived on σi and σi,max are calculated, respectively. Additionally, gamma index formalism for 2%/2 mm criteria is used. Once and for all, we typically take a good agreement between simulation MC GATE 9.0 and the experiment data with an error less than 2%/2 mm.ConclusionsIn the field of X-ray photons, a significant contribution of electrons and positrons has been found. This contribution could be enough to be essential or affect the delivered dose. A good agreement of 98% between this new approach of simulation MC GATE 9.0 software based on IAEA phase space and experimental dose distributions is observed regarding the validation tests used in this task.

The use of diisopropyl xanthogen polysulfide as a potential accelerator in efficient sulfur vulcanization of natural rubber compounds

AbstractWith the emerging concerns on the use of nitrosamine evolving accelerators, safer alternatives are desirable for the rubber industry. In the present study, cure characteristics, physicomechanical properties, crosslink density, aging, dynamic mechanical, and thermal properties of vulcanizates prepared with two nitrosamine safe binary accelerator systems containing diisopropyl xanthogen polysulfide (DIXP) and tetrabenzyl thiuram disulfide (TBzTD), and DIXP and dibenzyl dithiocarbamate (ZBeC) were investigated for efficient sulfur vulcanization of natural rubber (NR) compounds. Synergistic effect in both cure and physicomechanical properties was observed for all the combinations of the two accelerator systems. The composition containing DIXP with a lower loading (0.6 phr) of TBzTD, and ZBeC, demonstrated the highest technological performance. Retention of tensile properties on oxidative aging was highest for the vulcanizate prepared with DIXP/TBzTD (1.4/0.6). Dynamic mechanical and thermogravimetric analysis further confirmed the crosslink density and thermal stability of the network structure of the binary systems. In overall, DIXP shows the potential to be used as a safer accelerator in the manufacture of appropriate dry NR‐based rubber products.

Experimental Evaluation of Sub-Sampling IQ Detection for Low-Level RF Control in Particle Accelerator Systems.

The low-level radio frequency (LLRF) control system is one of the fundamental parts of a particle accelerator, ensuring the stability of the electro-magnetic (EM) field inside the resonant cavities. It leverages on the precise measurement of the field by in-phase/quadrature (IQ) detection of an RF probe signal from the cavities, usually performed using analogue downconversion. This approach requires a local oscillator (LO) and is subject to hardware non-idealities like mixer nonlinearity and long-term temperature drifts. In this work, we experimentally evaluate IQ detection by direct sampling for the LLRF system of the Polish free electron laser (PolFEL) now under development at the National Centre for Nuclear Research (NCBJ) in Poland. We study the impact of the sampling scheme and of the clock phase noise for a 1.3-GHz input sub-sampled by a 400-MSa/s analogue-to-digital converter (ADC), estimating amplitude and phase stability below 0.01% and nearly 0.01°, respectively. The results are in line with state-of-the-art implementations, and demonstrate the feasibility of direct sampling for GHz-range LLRF systems.

Stimulation of University Technological Entrepreneurship: Experience of Portugal and Estonia

An analysis of foreign experience convincingly shows that the level of science intensity of national products is directly related to the country’s position in international rankings of the productivity of university ecosystems. With a share of 0.4% in the global number of start-ups, Russia is inferior not only to developed countries but also to the BRICS countries. As of 2020, only 37 start-ups per million population are being created in the Russian Federation, while Switzerland has 1791. At the same time, in the jurisdiction of Russia, out of the total number founded in 2010–2019 start-ups remained no more than 36%. The strategies allow universities to create successful technological innovation ecosystems in the cultural, economic, and socio-political environment, which cannot be characterized as favorable for academic entrepreneurship. The analysis of factors stimulating the development of start-up ecosystems in Estonia and Portugal, including simplified residency programs for founders of foreign start-ups; ease of registration, business and taxation system; presence in the country of representative offices of large international companies and the creation of technological hubs for them, a developed system of national incubators and accelerators, including those financed by the state; safety, low cost of housing and living and comfortable living environment.

Reduced bandwidth Compton photons from a laser-plasma accelerator using tailored plasma channels

It has been demonstrated experimentally that laser plasma accelerators can produce multi-100 MeV electron bunches with a few percent energy spread, and from these electrons, multi-MeV quasi-monoenergetic photons have been demonstrated based on Compton up-scattering from a counter-propagating laser. This offers the potential of a high-quality, narrow-bandwidth, compact, photon source with broad application. The bandwidth of the resulting photons depends directly on the distribution of the electron bunch and is limited, in particular, by the bunch divergence (i.e., the spread in transverse velocity angle). At the same time, the ability to decelerate electrons after scattering is important to source deployment. We describe a series of plasma structures that expand and then collimate the electron bunch, reducing its divergence and thus reducing the bandwidth of the scattered photons while enabling both high performance scattering and deceleration. These plasma structures are demonstrated in simulations of the accelerator system, showing the potential to reach few-percent photon spread which is important for applications using nuclear resonance fluorescence.

First Proof-of-Concept Prototype of an Additive Manufactured Radio Frequency Quadrupole

Continuous developments in additive manufacturing (AM) technology are opening up opportunities in novel machining, and improving design alternatives for modern particle accelerator components. One of the most critical, complex, and delicate accelerator elements to manufacture and assemble is the radio frequency quadrupole (RFQ) linear accelerator, which is used as an injector for all large modern proton and ion accelerator systems. For this reason, the RFQ has been selected by a wide European collaboration participating in the AM developments of the I.FAST (Innovation Fostering in Accelerator Science and Technology) Horizon 2020 project. The RFQ is as an excellent candidate to show how sophisticated pure copper accelerator components can be manufactured by AM and how their functionalities can be boosted by this evolving technology. To show the feasibility of the AM process, a prototype RFQ section has been designed, corresponding to one-quarter of a 750 MHz 4-vane RFQ, which was optimised for production with state-of-the-art laser powder bed fusion (L-PBF) technology, and then manufactured in pure copper. To the best of the authors’ knowledge, this is the first RFQ section manufactured in the world by AM. Subsequently, geometrical precision and surface roughness of the prototype were measured. The results obtained are encouraging and confirm the feasibility of AM manufactured high-tech accelerator components. It has been also confirmed that the RFQ geometry, particularly the critical electrode modulation and the complex cooling channels, can be successfully realised thanks to the opportunities provided by the AM technology. Further prototypes will aim to improve surface roughness and to test vacuum properties. In parallel, laboratory measurements will start to test and improve the voltage holding properties of AM manufactured electrode samples.

A simplified analytical model to simulate martensite reorientation and plasticity in shape memory alloy ring couplers

Recent studies on Shape Memory Alloy rings have been undertaken at the European Organization for Nuclear Research (CERN) to develop smart and leak-tight couplers for Ultra High Vacuum systems of particle accelerators. A special thermo-mechanical process (training) is needed to provide SMA rings with proper functional properties, that is to allow thermal mounting, dismounting, and leak tight coupling within a given service temperature window. Low temperature ring expansion is a crucial part of the training process as it gives suitable size, shape recovery properties, and thermal stability range to the SMA element. An analytical model, based on simplified elastic-plastic axisymmetric concepts, has been developed and implemented in a commercial software to simulate isothermal SMA rings expansions. It is particularly useful to predict the final size of a martensitic SMA coupler as a function of the initial dimensions and of the pre-deformation parameters. The effectiveness of the model has been demonstrated by analyzing the stress/deformation field occurring in a wide range of ring geometries for different load cases including martensite reorientation and plasticity. The predictions of the analytical model have been systematically compared with those obtained by axisymmetric finite element (FE) analyses based on elastic-plastic constitutive models and experimental measurements.

Organizational and economic mechanism of the automatic underground train operation system

This work deals with the provision of underground, as one of the main modes of public transport, with automated control systems, in particular the provision of automated train management. It defines that the underground is one of the most progressive modes of transport, which is related to its environmental safety, comfort, and speed of movement, as this mode of transport does not intersect with other transport and pedestrian routes, which excludes traffic blocks. Underground is an important element of urbanized spaces, for it serves large passenger traffic. The article presents an algorithm for the creation of an automated control system for the underground train system. Based on this algorithm, a model of building an organizational and economic mechanism for automation of control systems has been developed. The diagram of organizational and technical implementation of the automated system of underground train management is presented. An economic analysis of the effectiveness of the application of the automated control system of underground trains was carried out. The recoupment on the acquisition and installation of automation systems is very high. The application of the automated system will increase the capacity of the underground by optimizing the traffic schedules, which will contribute to increasing its profitability. It is also useful to determine the reduction of electricity consumption due to the change in the dynamics of acceleration and braking systems, which is important, as the underground is a powerful enterprise. In the future, a promising direction is to streamline the coordination of train schedules and other modes of land public transport.