Single Disk Research Articles

On windage losses in high-speed pinion-gear pairs

This article deals with the Windage Power Losses (WPL) of pinion-gear pairs rotating in air. The WPL of several disks, spur and helical gears have been measured using a dedicated test rig developed from a WPL measurement system initially used for one single pinion or disk. In practice, several gears are in mesh and the windage losses for coupled pinion-gear systems need to be addressed. It is experimentally confirmed that, although some couplings can be identified between two rotating gears, the total WPL can be estimated as the sum of that of each individual member.

Observation of “Dark” Axisymmetric Plasma Modes in a Single Disk of Two-Dimensional Electrons

The microwave absorption spectra of a two-dimensional electron system based on GaAs/AlGaAs heterostructures in a perpendicular magnetic field are experimentally investigated. A unique noninvasive technique for the excitation of “dark” axisymmetric plasma oscillations in single disks of two-dimensional electrons is developed. The excitation conditions and physical properties of the new dark plasma modes are studied in detail. The experimental results are in excellent agreement with theoretical calculations.

Носії довготермінового зберігання даних

The results of the analysis of media development technologies for long-term data storage are presented. It is shown that the use of hard disk drive and solid-state non-volatile media only partially solve the problem of long-term information storage. Particular attention is paid to modern technologies for storing data on optical media. It is shown that the latest developments of optical media are aimed at a significant increase of optical media capacity by means of the nanostructured recording materials use. It was shown that maintaining of the big data security and integrity includes request stability of the readout signal contrast and data errors rates for long and fixed period of time. Therefore capacity of single disk for long data memory should be high enough to store the whole data to avoid the variation of the baseline over many disks. It was proposed to develop optical storage based on a nanoplasmonic hybrid glass matrix. The nanoplasmonic hybrid glass composite has to be formed by a sol-gel process to incorporate gold nanorods into hybrid glass composite. Incorporation of the inorganic phase increases the local Young’s modulus of the host matrix around nanorods which helps to improve the lifespan of the shape of nanorods by removing the unwanted shape degradation susceptible to the environmental thermal perturbation and increase lifespan of the data storage. Proposed method could be compared with the spin coating method, paving a way to the low-cost large-scale mass production of the optical disks.

Signal template generation from acquired images for model observer-based image quality analysis in mammography.

Mammography images undergo vendor-specific processing, which may be nonlinear, before radiologist interpretation. Therefore, to test the entire imaging chain, the effect of image processing should be included in the assessment of image quality, which is not current practice. For this purpose, model observers (MOs), in combination with anthropomorphic breast phantoms, are proposed to evaluate image quality in mammography. In this study, the nonprewhitening MO with eye filter and the channelized Hotelling observer were investigated. The goal of this study was to optimize the efficiency of the procedure to obtain the expected signal template from acquired images for the detection of a 0.25-mm diameter disk. Two approaches were followed: using acquired images with homogeneous backgrounds (approach 1) and images from an anthropomorphic breast phantom (approach 2). For quality control purposes, a straightforward procedure using a single exposure of a single disk was found adequate for both approaches. However, only approach 2 can yield templates from processed images since, due to its nonlinearity, image postprocessing cannot be evaluated using images of homogeneous phantoms. Based on the results of the current study, a phantom should be designed, which can be used for the objective assessment of image quality.

Piezoelectric-on-silicon Lorentz force magnetometers based on radial contour mode disk resonators

In this paper, we realize two unique design topologies for Lorentz force magnetometers (LFMs) based on radial contour (RC) mode piezoelectric-on-silicon disk resonators for the detection of out-of-plane magnetic fields (i.e. normal to the plane of fabrication). The proposed topologies take advantage of the strong electromechanical coupling from the piezoelectric Aluminum Nitride (AlN) layer to enhance the sensitivity of the devices while operating under ambient pressure, thus avoiding the need for vacuum encapsulation. Compared to previously reported modes, we show that RC mode provides a higher coupling efficiency. This ultimately leads to higher responsivity (defined here as the ratio of the pre-amplified output resonant current to the external magnetic field strength, normalized over the excitation current applied) compared to other modes previously reported. Having shown the advantages of the disk LFM, we then extend the advantages of a single disk LFM by mechanically coupling two disk resonators to increase the responsivity. We show that the quality (Q) factor, which determines the responsivity at resonance, does not degrade substantially by mechanically coupling the disks. The responsivity of our coupled disk LFM (21.20 ppm/mT) is 8 times higher compared to a state of art vacuum sealed LFM based on capacitive readout, but without the contraint of requiring vacuum.

Extraforaminal Lumbar Disk Herniations Lead To Neuroplastic Changes: a Study Using Quantitative Sensory Testing.

Extraforaminal lumbar disk herniations are characterized by distinct clinical features in comparison to paramedian lumbar disk herniations. We applied the quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain in 63 patients with a single lumbar disk herniation. They were categorized in 2 groups: (I) an intraspinal (group I; n = 47, 75%) and an extraforaminal (group E; n = 16, 25%). The wind-up ratio for assessing endogenous pain-modulating pathways was higher in group E (2.9 ± 2) than in group I (1.4 ± 1; P = 0.021). After a subsequent series of pinprick stimuli, an increase in pain assessed by the numeric rating scale could be shown in group E (2.1 ± 2 vs 1.1 ± 1; P = 0.032). Extraforaminal compression is associated with chronic as well as neuropathic pain, presumably caused by direct compression of the dorsal root ganglion, which may preferentially promote specific chronic pain mechanisms. Muscle Nerve 58: 676-680, 2018.

Cracked Insulator Detection Based on R-FCN

The insulator is an important component of the high voltage transmission line. Inspecting the defects of the insulator plays an important role in ensuring the normal operation of the transmission line. The cracked insulator is the most common type of insulator defects. The traditional cracked insulator detection method is to use image denoising, single insulator disk segmentation, and the adjacent European distance to locate and identify cracked insulators. Experiments show that the robustness of these methods is poor and their ability to adapt to the environment is not good. Image denoising and image segmentation with the complex environment in images are very difficult tasks. Based on the extracted insulator strings, we change the problem to cracked insulators detection under complex conditions with deep learning. Region-based Fully Convolutional Networks (R-FCN), a deep learning algorithm, is adopted. Firstly, we apply image correction and cropping to images with different sample sizes and directions. Secondly, we use image enhancement technology to expand the dataset of samples. Finally, sliding window and coordinate mapping method are used when testing samples. The experimental results after the algorithm being applied to UVA dataset show an average accuracy rate of 90.5%. The inspection time of a single image is less than 1 second, and the model proposed in this paper has strong robustness and environmental adaptability.

Mass Distribution in Stellar Structures of Local Dwarfs

AbstractWe study the distribution of mid-infrared light in stellar structures in a large sample (∽ 400) of low-mass (Mstellar <109 MSun) galaxies. Our sample is selected from the Spitzer Survey of Stellar Structures in Galaxies (S4G), which entails deep imaging of nearby galaxies with the IRAC instrument at 3.6/4.5 μ m. Based on the 2D decomposition of the 3.6μ m images, we find that the majority (∽65%) of galaxies in our sample is well-fit by a single disk profile. The rest of the sample is more adequately fit by a disk and an additional component (e.g., bar, nucleus, bulge, second disk component). Bars are present in ∽11% of the sample, marking a sharp drop in the bar fraction compared to that found for more massive galaxies. The typical contribution of bars to the 3.6 μ m light in dwarfs is ∽1-2%, lower than that found in more massive galaxies. These results bring a number of issues into question: why do low-mass galaxies have such low bar fraction? does the bar instability act differently in low-mass galaxies such that a smaller proportion of stellar mass is typically involved in the bar structure? Is the fact that dwarfs are more dark matter dominated playing a role?

An impedimetric bioaffinity sensing chip integrated with the long-range DC-biased AC electrokinetic centripetal vortex produced in a high conductivity solution.

Immunoreaction of specific antibodies to antigens is widely used in numerous immunoanalysis applications. However, diffusion-dominated transport in stationary solutions limits the rate and binding density of immunoreaction. This research describes the construction of chip-type concentric multi-double ring electrodes and single central disk electrode. A +1 V-biased 6 Vpp voltage was applied to the multi-double ring electrodes to induce a long-range DC-biased AC electrokinetic flow (ACEKF). The immunoreaction was quantified by electrochemical impedance spectrum (EIS). Fluorescence-labeled secondary antibody (FLSA) and protein A were exemplified as an immunoreacting model to demonstrate the effect of ACEKF on immunoreaction efficiency. The results showed that FLSA binding can reach a plateau in 8 min with the DC-biased ACEKF vortex, and the increment of electron transfer resistance is 2.26 times larger than that obtained in the unstirred solution. The sensitivity of the calibration curves obtained by EIS detection with the aid of DC-biased ACEKF vortex is 1.51 times larger than that obtained in an unstirred solution. The label-free EIS-based sensing chip integrated with the long-range DC-biased ACEKF vortex promises to facilitate immunoreaction efficiency, which is beneficial for the development of a miniature and fast-detection in vitro diagnostic device.

Transition to turbulence in the rotating disk boundary layer of a rotor–stator cavity

The transition to turbulence in the rotating disk boundary layer is investigated in a closed cylindrical rotor–stator cavity via direct numerical simulation (DNS) and linear stability analysis (LSA). The mean flow in the rotor boundary layer is qualitatively similar to the von Kármán self-similarity solution. The mean velocity profiles, however, slightly depart from theory as the rotor edge is approached. Shear and centrifugal effects lead to a locally more unstable mean flow than the self-similarity solution, which acts as a strong source of perturbations. Fluctuations start rising there, as the Reynolds number is increased, eventually leading to an edge-driven global mode, characterized by spiral arms rotating counter-clockwise with respect to the rotor. At larger Reynolds numbers, fluctuations form a steep front, no longer driven by the edge, and followed downstream by a saturated spiral wave, eventually leading to incipient turbulence. Numerical results show that this front results from the superposition of several elephant front-forming global modes, corresponding to unstable azimuthal wavenumbers $m$, in the range $m\in [32,78]$. The spatial growth along the radial direction of the energy of these fluctuations is quantitatively similar to that observed experimentally. This superposition of elephant modes could thus provide an explanation for the discrepancy observed in the single disk configuration, between the corresponding spatial growth rates values measured by experiments on the one hand, and predicted by LSA and DNS performed in an azimuthal sector, on the other hand.

A high-performance virtual machine filesystem monitor in cloud-assisted cognitive IoT

Cloud-assisted Cognitive Internet of Things has powerful data analytics abilities based on the computing and data storage capabilities of cloud virtual machines, which makes protecting virtual machine filesystem very important for the whole system security. Agentless periodic filesystem monitors are optimal solutions to protect cloud virtual machines because of the secure and low-overhead features. However, most of the periodic monitors usually scan all of the virtual machine filesystem or protected files in every scanning poll, so lots of secure files are scanned again and again even though they are not corrupted. In this paper, we propose a novel agentless periodic filesystem monitor framework for virtual machines with different image formats to improve the performance of agentless periodic monitors. Our core idea is to minimize the scope of the scanning files in both file integrity checking and virus detection. In our monitor, if a file is considered secure, it will not be scanned when it has not been modified. Since our monitor only scans the newly created and modified files, it can check fewer files than other filesystem monitors. To that end, we propose two monitor methods for different types of virtual machine disks to reduce the number of scanning files. For virtual machine with single disk image, we hook the backend driver to capture the disk modification information. For virtual machine with multiple copy-on-write images, we leverage the copy-on-write feature of QCOW2 images to achieve the disk modification analysis. In addition, our system can restore and remove the corrupted files. The experimental results show that our system is effective for both Windows and Linux virtual machines with different image formats and can reduce the number of scanning files and scanning time.

Writing and storing information in an array of magnetic vortex nanodisks using their azimuthal modes

The switching of a vortex core of a single disk in an array of a multilayer system is investigated by micromagnetic simulation. We found that the perpendicular uniaxial anisotropy decreases the frequencies of the azimuthal mode in disks with magnetic vortex configuration. We obtained a phase diagram of magnetic field intensity vs. frequency of the azimuthal mode, as a function of the value of perpendicular uniaxial anisotropy. We demonstrated that rotating magnetic fields (CW and CCW) with frequency equal to azimuthal modes can be used to switch the vortex core of single disks in a disk array. This allows obtaining different memory states with a single array of nanodisks, and therefore writing information through the application of rotating fields.

Climate sensitivity is affected by growth differentiation along the length of Juniperus communis L. shrub stems in the Ural Mountains

Arctic and alpine shrubs are valuable for future dendro-ecological and dendro-climatological studies in regions where trees are sparse or absent. A commonly accepted procedure of sampling shrub stem disks is at the root collar. However many shrub studies report low inter-series correlations in radial measurements as compared to trees. Many studies also report cross-dating difficulties with radial measurements from shrubs within a stand and commonly attribute this to differential growth along the length of the stem. So does one stem disk entirely represent the environmental parameters the shrub might be reacting to? Does change in sampling location of the stem disk affect the subsequent ring-width chronologies and climate sensitivity? To tackle these questions, we investigated Juniperus communis L. – a species wide spread in the circumpolar arctic – across a latitudinal gradient in the Ural Mountains. Based on traditional radial ring-width measurements we assessed growth synchronicity along the length of shrub stems. We also compared ring width chronologies representing different stem heights with respect to their relationships with temperature and the standardized precipitation evapotranspiration index (SPEI). Growth patterns often varied significantly among stems disks of the same shrubs, resulting in dissimilar climate-growth relationships of stem disk chronologies. For correlations with temperature, stem disks at 20 cm distance from the root collar captured the best signal. For correlations with SPEI data we could not find any specific stem disk chronology with highest sensitivity. At least in our dataset, no “perfect sampling height” with high climate sensitivity exists and our results thus highlight that a single stem disk from a shrub may not completely represent the shrub’s growth response to climate parameters.

Antimicrobial susceptibility testing of Finnish Bordetella pertussis isolates collected during 2006-2017.

Macrolides, such as azithromycin and erythromycin, are first-line drugs for the (prophylactic) treatment of pertussis. This study aimed to screen for macrolide-, quinolone- or trimethoprim/sulfamethoxazole (SXT)-resistant strains among Finnish Bordetella pertussis isolates. Antimicrobial susceptibility testing was performed on 148 B. pertussis strains isolated during 2006-2017. Isolates were analysed by allele-specific PCR for detection of the macrolide resistance-associated mutation A2047G in the 23S rRNA gene. The gyrA gene was sequenced for detection of the A260G mutation associated with quinolone resistance. For phenotyping, a random selection was made by selecting every third isolate (n=50) to determine the minimum inhibitory concentrations (MICs) for erythromycin and azithromycin by Etest and the inhibition zone size for nalidixic acid (NAL) and SXT by single disk diffusion assay. Neither the macrolide resistance-associated mutation A2047G nor the quinolone resistance-associated mutation A260G was detected in any of the B. pertussis isolates. MICs of azithromycin and erythromycin ranged between 0.016-0.19μg/mL and 0.016-0.25μg/mL, respectively. The size of the inhibition zone surrounding the NAL disk ranged between 22-27mm in diameter. The inhibition zone surrounding the SXT disk ranged between 24-37mm in diameter. No isolates resistant to any of the tested antimicrobials were identified. The allele-specific PCR is a simple and useful tool for screening B. pertussis resistance to macrolides. All Finnish isolates tested were susceptible to macrolides, quinolones and SXT.

Fracta-­like Microreactor for Hydrogen Production

A catalyst micro­channel reactor using Cu/Alumina as the catalyst was designed in order to produce hydrogen from methanol in order to provide a fuel source to a hydrogen fuel cell to meet a power demand of 100W. To do this a branched channel micro­reactor design was employed. The reasoning for this was that the increased pressure drop due to the branching network and increased surface area of the reactor would produce a greater hydrogen yield then that of a straight channel reactor. The branched channel reactor showed a 10% greater hydrogen yield then that of the straight channel under three different conditions which the initial flow rate of methanol was varied. The final design of the reactor to meet the 100W power demand was a stack of 48 single branch disk units, each 17.5 mm in diameter, 1 mm thick, a constant channel depth of 250 µm, and a outlet channel width of 100 µm

Hybrid modeling and verification of disk-stacked shock absorber valve

The mathematical model of valve deformation of hydraulic shock absorber is established using the hybrid method of large deflection and beam deflection. The model can be used for design purposes and helps in developing damping valve based on single disk and shim stack. The model of the hydraulic shock absorber with valve system consists of shim stack and a spring preloaded disk is developed using AMESim. The correctness of the mathematical model of the valve deformation based on the hybrid method and the simulation model using AMESim is verified by the shock absorber bench test, which proves the method proposed in this article is reasonable and reliable. It is significant for reference in the design and development of hydraulic shock absorber.

IR+: Removing parallel I/O interference of MPI programs via data replication over heterogeneous storage devices

Abstract I/O requests from parallel processes to a disk compete with each other for a single disk head to access data. The disk efficiency can be significantly reduced due to frequent disk head seeks. In this paper, we propose a scheme, named IR+, to eliminate I/O interference for a single MPI program on disks by taking advantage of optimized access patterns and heterogeneous storage devices (e.g., solid-state disks). It identifies segments of files that could be involved in the interfering accesses and replicates them to their respectively designated storage servers. Moreover, it can further improve I/O performance by storing replicas on SSDs when accessing the on-disk replicas cannot sufficiently address the issue. IR+ has been implemented in the MPI library for high portability on top of the Lustre parallel file system. Our experiments with representative benchmarks, such as NPB BTIO and GTS , show that it can significantly improve I/O performance on the production HPC systems.

Friction and diffusion of a nano-colloidal disk in a two-dimensional solvent with a liquid-liquid transition.

We report on the friction and diffusion of a single mobile nano-colloidal disk, whose size and mass are one and two orders of magnitude, respectively, greater than the molecules of the host solvent; all particles are restricted to move in a two-dimensional space. Using molecular dynamics simulations, the variation of the transport coefficients as a function of the thermodynamic state of the supporting fluid, in particular, around those states in the neighbourhood of the liquid-liquid phase coexistence, is investigated. The diffusion coefficient is determined through the fit of the mean-square displacement at long times and with the Green-Kubo relationship for the velocity autocorrelation function, whereas the friction coefficient is computed from the correlation of the fluctuating force. From the determination of the transport properties, the applicability of the Stokes-Einstein relation in two dimensions around the second critical point is discussed.

Calibration testing of discs using photoelasticity method

Using of the photoelasticity method for determining the stresses under the action of specified forced deformations and, in particular, temperature deformations, which do not satisfy the compatibility conditions, is relevant in the study of composite structures. Photoelasticity method, which is a continual method, and the method of “defrosting” forced deformations, as its subsection, allow obtaining a stress-strain state in the composite area with forced deformations on models made of optically - responsive material. The method of defrosting forced deformations, using the procedure of preliminary freezing of model elements with subsequent defrosting of the entire model, is an effective, versatile and promising method for simulation of stresses as a result of specified forced deformations. In the study of composite structures by the method of photoelasticity and defrosting “defrosting” of forced deformations, a model composed of elements with previously created forced deformations is created. To determine the created forced deformations, calibration tests are performed, in which the following actual loads are determined: forced deformations, pressure, optical and mechanical characteristics of the model material: modulus of elasticity, material fringe value. Novelty of the calibration test method is the definition of “frozen” forced deformations in the blank of the photoelasticity model using a single composite disk model without testing additional models - beams [1, 2]. Taken into account the material parameters of model: Young's modulus, the price of a polymeric material strip, which are different for batches of initial components: epoxy resin and anhydrite. In order to approve the results of calibration tests, this paper considers the theoretical and experimental solution of the elasticity test problem for a composite disk, one of the areas of which is uniformly heated. The obtained data are used for calibration tests in determining the actual loads and mechanical characteristics in the model sections.

DPPDL: A Dynamic Partial-Parallel Data Layout for Green Video Surveillance Storage

Video surveillance requires storing massive amounts of video data, which results in the rapid increasing of storage energy consumption. With the popularization of video surveillance, green storage for video surveillance is very attractive. The existing energy-saving methods for massive storage mostly concentrate on the data centers, mainly with random access, whereas the storage of video surveillance has inherent workload characteristics and access pattern, which can be fully exploited to save more energy. A dynamic partial-parallel data layout (DPPDL) is proposed for green video surveillance storage. It adopts a dynamic partial-parallel strategy, which dynamically allocates the storage space with an appropriate degree of partial parallelism according to performance requirement. Partial parallelism benefits energy conservation by scheduling only partial disks to work; a dynamic degree of parallelism can provide appropriate performances for various intensity workloads. DPPDL is evaluated by a simulated video surveillance consisting of 60–300 cameras with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1920 \times 1080$ </tex-math></inline-formula> pixels. The experiment shows that DPPDL is most energy efficient, while tolerating single disk failure and providing more than 20% performance margin. On average, it saves 7%, 19%, 31%, 36%, 56%, and 59% more energy than a CacheRAID, Semi-RAID, Hibernator, MAID, eRAID5, and PARAID, respectively.