Miniature Acceleration Research Articles

Investigation on the multidirectional crack vibration induced by rock fracture

Understanding crack vibrations in rock under load is crucial for comprehending and predicting rock failure. With this motive, a novel multidirectional crack vibration (MCV) monitoring experiment is carried out using miniature vibration acceleration sensors with directional sensing. The obtained results show that the crack surface produced by uniaxial compression failure of rock is rough and its direction is variable. Furthermore, the volume distribution of the sample after failure is uneven, and there is a noticeable difference in mass between the broken samples on either side of the crack. Different directions of crack vibration signals were detected during rock failure, all exhibiting a strong temporal correspondence with the stress drop, but the amplitudes and main frequencies of the vibrations differ across directions. The fracture-induced crack vibration is a typical low-frequency signal, with the highest recorded frequency at 55.63 kHz and the lowest being 0.86 kHz, with the main frequency mostly below 25 kHz, which is notably lower than acoustic emission. This difference suggests that fracture-induced crack vibration and acoustic emission are distinct physical quantities. The disparities in rock vibration amplitude and main frequency among different directions, especially those perceived by opposing sensors, indicate that the two sides of the crack cannot be considered as the same vibration system. The analysis shows that the fracture-induced crack vibration of rock under load is damped vibration with a small and variable damping. Besides, due to the difference in vibration parameters on both sides of the crack, their vibration amplitude and frequency are also different. The miniature acceleration sensors used in this work can effectively capture MCV during rock failure and can be employed to further investigate the vibration precursor of rock instability failure, so as to develop appropriate assessment and prediction methods for underground dynamic disasters.

Phenotypes for general behavior, activity, and body temperature in 3q29 deletion model mice

Whole genome analysis has identified rare copy number variations (CNV) that are strongly involved in the pathogenesis of psychiatric disorders, and 3q29 deletion has been found to have the largest effect size. The 3q29 deletion mice model (3q29-del mice) has been established as a good pathological model for schizophrenia based on phenotypic analysis; however, circadian rhythm and sleep, which are also closely related to neuropsychiatric disorders, have not been investigated. In this study, our aims were to reevaluate the pathogenesis of 3q29-del by recreating model mice and analyzing their behavior and to identify novel new insights into the temporal activity and temperature fluctuations of the mouse model using a recently developed small implantable accelerometer chip, Nano-tag. We generated 3q29-del mice using genome editing technology and reevaluated common behavioral phenotypes. We next implanted Nano-tag in the abdominal cavity of mice for continuous measurements of long-time activity and body temperature. Our model mice exhibited weight loss similar to that of other mice reported previously. A general behavioral battery test in the model mice revealed phenotypes similar to those observed in mouse models of schizophrenia, including increased rearing frequency. Intraperitoneal implantation of Nano-tag, a miniature acceleration sensor, resulted in hypersensitive and rapid increases in the activity and body temperature of 3q29-del mice upon switching to lights-off condition. Similar to the 3q29-del mice reported previously, these mice are a promising model animals for schizophrenia. Successive quantitative analysis may provide results that could help in treating sleep disorders closely associated with neuropsychiatric disorders.

Experimental Investigations on the Response of Bedload Sediment to Vibration

Research results on sediment vibration characteristics are scarce, and knowledge on the effect of the particle size on the sediment vibration response is still limited. In this study, natural pebbles of different heights—A, B and C—were selected (hA < hB < hC). Miniature acceleration sensors were installed inside the pebble. Experimental methods were used to measure the vibration process of pebbles on the rough bed surface and to measure the near-bed velocities simultaneously. The test results show that the sequence of pebble vibration and entrainment is A-C-B as the flow rate increases. The vibration intensity of pebbles A and B tended to increase before approaching the entrainment threshold but weakened when approaching the entrainment threshold; the vibration frequency, on the contrary, first decreased and then increased. The vibration intensity of pebble C decreased first and then increased, and when approaching the entrainment threshold, it rolled directly. The vibration frequency first increased and then decreased, and near the entrainment threshold, there was no vibration. Thus, it was demonstrated that with the increase in pebble height, the average vibration intensity increases, and the average vibration frequency decreases. The results of this research provide a reference for exploring the dynamic mechanism of the bed load in mountain rivers.

XIORT-MC: A real-time MC-based dose computation tool for low- energy X-rays intraoperative radiation therapy.

The INTRABEAM system is a miniature accelerator for low-energy X-ray Intra-Operative Radiation Therapy (IORT), and it could benefit from a fast and accurate dose computation tool. With regards to accuracy, dose computed with Monte Carlo (MC) simulations are the gold standard, however, they require a large computational effort and consequently they are not suitable for real-time dose planning. This work presents a comparison of the implementation on Graphics Processing Unit (GPU) of two different dose calculation algorithms based on MC phase-space (PHSP) information to compute dose distributions for the INTRABEAM device within seconds and with the accuracy of realistic MC simulations. The MC-based algorithms we present incorporate photoelectric, Compton and Rayleigh effects for the interaction of low-energy X-rays. XIORT-MC (X-ray Intra-Operative Radiation Therapy Monte Carlo) includes two dose calculation algorithms; a Woodcock-based MC algorithm (WC-MC) and a Hybrid MC algorithm (HMC), and it is implemented in CPU and in GPU. Detailed MC simulations have been generated to validate our tool in homogeneous and heterogeneous conditions with all INTRABEAM applicators, including three clinically realistic CT-based simulations. A performance study has been done to determine the acceleration reached with the code, in both CPU and GPU implementations. Dose distributions were obtained with the HMC and the WC-MC and compared to standard reference MC simulations with more than 95% voxels fulfilling a 7%-0.5mm gamma evaluation in all the cases considered. The CPU-HMC is 100 times more efficient than the reference MC, and the CPU-WC-MC is about 50 times more efficient. With the GPU implementation, the particle tracking of the WC-MC is faster than the HMC, with the extraction of the particle's information from the PHSP file taking a major part of the time. However, thanks to the variance reduction techniques implemented in the HMC, up to 400 times less particles are needed in the HMC to reach the same level of noise than the WC-MC. Therefore, in our implementation for INTRABEAM energies, the HMC is about 1.3 times more efficient than the WC-MC in an NVIDIA GeForce GTX 1080 Ti card and about 5.5 times more efficient in an NVIDIA GeForce RTX 3090. Dose with noise below 5% has been obtained in realistic situations in less than 5 s with the WC-MC and in less than 0.5 s with the HMC. The XIORT-MC is a dose computation tool designed to take full advantage of modern GPUs, making possible to obtain MC-grade accurate dose distributions within seconds. Its high speed allows a real-time dose calculation that includes the realistic effects of the beam in voxelized geometries of patients. It can be used as a dose-planning tool in the operating room during a XIORT treatment with any INTRABEAM device.

Determination of paramagnetic ferrous gel sensitivity in low energy x-ray beam produced by a miniature accelerator.

The INTRABEAM Carl Zeiss Surgical system (Oberkochen, Germany) is a miniature accelerator producing low energy photons (50 keV maximum). The published dosimetric characterization of the INTRABEAM was based on detectors (radiochromic films or ionization chambers) not allowing measuring the absorbed dose in the first millimeters of the irradiated medium, where the dose is actually prescribed. This study aims at determining with Magnetic Resonance Imaging (MRI) the sensitivity of a paramagnetic gel in order to measure the dose deposit produced with the INTRABEAM from 0 to 20 mm. Although spherical applicators are mostly used with the INTRABEAM system for breast applications, this study focuses on surface applicators that are of interest for cutaneous carcinomas. The irradiations at 12 different dose levels (between 2 Gy and 50 Gy at the gel surface) were performed with the INTRABEAM and a 4 cm surface applicator. The gel used in this study is a new « sensitive » material. In order to compare gel sensitivity at low energy with high energy, gels were irradiated by an 18 MV photon beam produced by a Varian Clinac 2100 CD. T2 weighted multi echo MRI sequences were performed with 16 echo times. The T2 signal versus echo times was fitted with a mono-exponential function with 95% confidence interval. The calibration curve determined at low energy is a linear function (r2 = 0.9893) with a sensitivity of 0.0381 s-1.Gy-1, a similar linear function was obtained at high energy (0.0372 s-1.Gy-1 with r2 = 0.9662). The calibration curve at low energy was used to draw isodose maps from the MR images. The PDD (Percent Depth Dose) determined in the gel is within 5%-1mm of the ionization chamber PDD except for one point. The dosimetric sensitivity of this new paramagnetic ferrous gel was determined with MRI measurements. It allowed measuring the dose distribution specifically in the first millimeters for an irradiation with the INTRABEAM miniature accelerator equipped with a surface applicator.

29. Dosimetric response of ferrous gels in a low energy beam produced by a mini-accelerator

Introduction The INTRABEAM® system is a miniature accelerator producing low energy photons (50 keV maximum). The published dosimetric characterization of the INTRABEAM system for flat and surface applicators [1] , [2] was based on detectors (radiochromic films or ionization chambers) not allowing measuring the absorbed dose in the first millimeters of the irradiated medium, where the dose is actually prescribed. This study aims at measuring the dose deposit produced with INTRABEAM surface applicators in the first millimeters by determining gel sensitivity with Magnetic Resonance Imaging (MRI). Methods The irradiations at different dose levels were performed with the INTRABEAM® Carl Zeiss Surgical system (Oberkochen, Germany)]. The gel used in this study is a new “sensitis” material which is described by Stien et al. [3] and V. Dedieu et al. [4] . Gel irradiation in tin containers was carried out for twelve dose levels between 2 Gy and 50 Gy at the gel surface with a 4 cm surface applicator. In order to compare gel sensitivity at low energy with high energy, gels in tins containers were irradiated by a 18 MV photon beam produced by a Varian Clinac 2100 CD. T2 weighted multi echo MRI sequences were performed with 16 echo times and TR = 2000 ms. The response in T2 was determined on Matlab (Version 7.11, MathWorks, Natrick, MA, US). Results The T2 signal versus echo times can be fitted with a mono-exponential function with 95% of confidence. The calibration curve determined from experiments with tins at low energy is a linear function (R2 = 0.964) with a sensitivity of 0.0422 s−1 Gy−1. It is of the same order of magnitude as the gel sensitivity found from experiments at high energy (0.0391 s−1 Gy−1 with R2 = 0.924). The calibration curve at low energy was used to obtain Isodose maps from images (Fig. 1). The PDD (Percent Depth Dose) determined in gel is similar to the one measured with an ionization chamber. Conclusions The dosimetric response of ferrous gels in a low energy beam produced by a mini -accelerator was determined with MRI measurements. It allowed measuring the dose distribution in particular in the first millimeters for an irradiation with the INTRABEAM® miniature accelerator equipped with a surface applicator. These results must be confirmed for the other diameters of surface applicators and for flat applicators as well.

Dosimetric characterization of INTRABEAM® miniature accelerator flat and surface applicators for dermatologic applications

PurposeThis study aims at characterizing the dosimetric behavior of an INTRABEAM® miniature accelerator equipped with flat and surface applicators, converting the spherical dose distribution into a flat one. MethodsDosimetric characterization was carried out in two steps. Firstly characterization was made in standard conditions for dermatologic applications, which is with the applicator directly on contact with the skin. Secondly, characterization was made in more clinical conditions, such as obliquities and heterogeneities. ResultsBehaviors of flat and surface applicators are different. Dose distribution for surface applicators is uniform at surface, whereas for flat applicator the maximum homogeneity is shown at a particular depth in water. Some results are different from previously published studies due to differences in the X-ray source design. The study showed that in the absence of a perfect contact between the applicator and the skin of the patient, there is a dose distribution spread on the edge of the irradiation field where the contact is not made. Dose loss due to lack of backscatter radiations is significant. By contrast, influence of a denser material behind the measurement point has no significant influence on the dose at this point. Thickness of tissue treated with flat and surface applicators is only a few millimeters, depending on the applicator's size, making these applicators ideal for superficial lesions, compared to high energy electrons and iridium brachytherapy. ConclusionsThe INTRABEAM® miniature accelerator equipped with surface applicators is a reliable way of treating superficial cutaneous malignancies.

Take-off performance of flying fish Cypselurus heterurus doederleini measured with miniature acceleration data loggers

Flying fish (Teleostei: Exocoetidae) glide at a speed considerably faster than they can travel in water. This phenomenon has been investigated and examined from taxonomic, anatom- ical, aerodynamic and biological standpoints through field observations. However, direct meas- urements of the flight performance of flying fish at the moment of leaping from the water surface have not previously been performed, due to the difficulty of monitoring gliding behavior. In the present study, we used recently developed data loggers capable of recording acceleration on a 3- dimensional axis to directly examine the gliding behavior of the flying fish Cypselurus heterurus doederleini under controlled conditions. Gliding behavior was assessed with the data logger fixed to the fish in 1 of 2 different positions, and positioning was not found to seriously affect leaping performance, as no effects on pitch angle, amplitude of fluctuation in swaying acceleration, stroke cycle frequency, or the duration of acceleration were observed. Pitch angle (20.0 ± 3.3°) and stroke cycle frequency (21.2 ± 4.6 Hz) were found to be lower in the present study than in previous stud- ies that examined gliding behavior in the field. Additionally, the flying fish were estimated to leap from the water surface at speeds of 3.9 to 5.2 m s �1 in our study, which is 38.7 to 51.5% of previ- ously reported maximum swimming speeds determined using stroboscopic filming. Our results suggest that the flying fish in our study may have recognized the capacity of the experimental space and regulated swimming performance before leaping from the water surface.

Making overall dynamic body acceleration work: on the theory of acceleration as a proxy for energy expenditure

Summary1. The energetic costs of different behaviours are critical in modulating the behavioural ecology of free‐living animals. Despite this, measurement of energy expenditure in the field has proved difficult.2. A new method with broad application for field studies has been proposed for determining the rate at which animals expend energy, based on measurements of overall dynamic body acceleration (ODBA) through the attachment of miniature acceleration data‐loggers. This technique is easy to implement and has the promise to be able to resolve energy expenditure with fine (sub‐second) temporal resolution, making it the only method which promises to able to determine the cost of short‐lived behaviours. Increasing evidence supports the validity of the approach although the rationale behind it is vague.3. This study explores link between metabolic energy and acceleration by examining what is known about how muscular tissue converts metabolic energy to mechanical work via muscular contraction and how Newtonian physics facilitates a derivation of Power (the rate at which work is performed) from acceleration. The link between metabolic energy and acceleration appears to involve three discrete processes: (i) the ratio of mechanical work to metabolic work performed by a single muscle (mechano‐chemical efficiency); (ii) the ratio of external and internal work performed (mechanical work of the limbs in relation to that of the centre of mass); and (iii) the ratio of inertial to de novo mechanical work. These processes may vary according to the animal’s mass, the medium in which it travels and its gait or behaviour.4. Assessment of movement has limited application in defining non‐movement energy expenditure such as that involved in specific dynamic action or non‐shivering thermogenesis. However, this non‐movement energy expenditure may often be modelled with reasonable confidence. The utility and appropriateness of the ODBA‐energy expenditure method depends on a set of conditions, which we define and suggest should be assessed a priori.5. This study explores the framework behind the ODBA‐energy expenditure method to enable informed decisions to be made regarding the suitability for specific research questions addressed, as well as highlighting calibration needs.

Accelerating estimates of activity-specific metabolic rate in fishes: Testing the applicability of acceleration data-loggers

We report the results of a series of experiments to test the utility of acceleration data-loggers for determining the energy expenditure of juvenile hammerhead sharks ( Sphyrna lewini). In one experiment, three sharks were instrumented with miniature acceleration data-loggers and swum in a Brett-style respirometer at a range of speeds. For all three sharks, significant linear relationships were obtained between mean oxygen consumption (M ·o 2) and Partial Dynamic Body Acceleration in the lateral and dorso-ventral axes (PDBA y, z ) with high predictive power ( r 2 > 0.71). In a second experiment, PDBA was measured for sharks swimming freely in circular tanks. The free-swimming sharks exhibited wide ranges of PDBA y, z ; routine swimming was characterised by low PDBA y, z (0.01–0.12 g) whereas unsteady swimming, (especially fast-start swimming of > 1 g) was characterised by high PDBA y, z . Despite initial evidence of linearity in the oxygen consumption vs. PDBA relationship, incorporating previous estimates of standard metabolic rate of hammerhead sharks suggests a non-linear fit. Further work is needed to establish the exact shape of the relationship beyond the narrow range of speeds that hammerhead pups could be exercised in this study, particularly the low swimming speeds which are frequently observed in free-swimming animals.

The Z machine: Powering up a miniature accelerator to target nuclear fusion

Science NewsVolume 153, Issue 3 p. 46-47 Article The Z machine: Powering up a miniature accelerator to target nuclear fusion Ivars Peterson, Ivars PetersonSearch for more papers by this author Ivars Peterson, Ivars PetersonSearch for more papers by this author First published: 30 June 2009 https://doi.org/10.2307/4010276AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume153, Issue317 January 1998Pages 46-47 RelatedInformation

A future AMS/chromatography instrument for biochemical and environmental measurements

A summary will be presented of an instrumentation study conceived to design a miniature accelerator mass spectroscopy (AMS) system. A secondary set of goals endeavoured to link the chemical specificity of gas and liquid chromatography with the ultra-sensitivity of AMS. The purpose of such combined instrumentation would be to permit 14C tracking of biochemical molecules and to provide identification of their metabolic products with a minimum of additional chemical manipulations. Features of a compact chromatograph/AMS system will be presented. Its size will make possible installation in hospitals and non-nuclear research institutions. The sensitivity suggests that, because only very low concentrations of radio-tracers will be needed, nuclear waste disposal problems will be minimized.

工具エンゲージにおける切削力

A design principle is proposed for the dynamometer which is equipped with an acceleration pick-up to measure the transient cutting force at the initial engagement of the tool with the workpiece (or tool impact) in interrupted cutting. The new dynamometer fitted with a miniature acceleration pick-up of 120 kHz natural frequency is proved to be capable of measur-ing the transient cutting force with a rise time of about 20 μs. on the pendulum cutting tester which was specially designed to analyse the transient phenomena at the tool impact. Using the dynamometer on the cutting tester as above, it is shown that there is no appreciable peak in the cutting force at the initial stage of the tool engagement, and that the transient vibration of the tool is strongly affected by the tool impact the intensity of which may be described by the reciprocal of the rise time of the transient cutting force.

Resonance transformer for miniature accelerator facilities

Resonance transformer for miniature accelerator facilities