Major earthquakes such as Kobe (1995), Kocaeli (1999) and Chi–Chi (Taiwan) have shown that underground structures have suffered significant damage due to dynamic loading. Therefore, recently, much ...priority has been given to seismic safety of underground structures located in earthquake-prone regions. There is, however, not much experimental research on the dynamic response of buried structures. This research aims to better understand the dynamic behavior of relatively flexible rectangular underground structures embedded in dry sand. To achieve this purpose, a series of dynamic centrifuge tests were conducted on a box-shaped flexible underground structure under harmonic motions with different accelerations and frequencies. Thus, response of soil and buried structure model was examined considering the dynamic soil structure interaction. Accelerometers were placed in the soil and on the buried structure model to evaluate the shear strain and acceleration response. Moreover, a special attempt was made to investigate the racking deformations by installing extensometers inside the tunnel model. Measurements obtained from those extensometers were compared with the predictions of analytical solutions. Results show that, Penzien’s approach gives reasonable estimates of racking deformation for the rectangular shaped flexible underground structure.
The potential application of geofoam in reducing the dynamic earth forces on flexible cantilever earth retaining walls was investigated through small-scale physical model tests. Tests were carried ...out using a state-of-the-art laminar container and a uniaxial shaking table. Deformable geofoam panels of low stiffness made from expanded polystyrene (EPS) and extruded polystyrene (XPS) geofoam were utilized as compressible inclusions in the present study. The dynamic stress-strain properties of these geomaterials are discussed based on results from laboratory cyclic triaxial tests. Lateral dynamic earth pressures and wall displacements at different elevations within the backfill were monitored during the application of various base excitations. The test results revealed that the presence of a deformable geofoam panel of low stiffness behind the flexible retaining wall will result in a reduction of the dynamic wall pressures and displacements. The geofoam efficiency in terms of load and displacement reduction decreases as the flexibility ratio of the model wall increases. On the other hand, load reduction efficiency of the geofoam increases as the amplitude and frequency ratio of the excitation increases. Load reduction efficiencies achieved in the tests were compared to those of the previous physical and numerical modeling studies available in the literature. Comparisons indicate that there is an agreement with the data presented in the previous modeling studies for low acceleration amplitudes and wall flexibility values, however, this agreement diminishes as wall flexibility begins to play role in reducing the earth pressures. Application point of the maximum dynamic thrust varies between 0.4H to 0.6H depending on the inclusion type, flexibility ratio of the wall and the characteristics of the harmonic motion applied to the base of the models.
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•Dynamic tests are performed on flexible retaining walls using a laminar container.•Effect of geofoam inclusion stiffness and wall flexibility on dynamic behavior was investigated.•Up to 50% reduction in dynamic pressures may occur for cantilever retaining walls.•Wall deflections contribute to the seismic load reduction efficiency of geofoam.
•Low cost rotating arm apparatus is used for low speed calibration.•Hot wire probe is calibrated for very low velocities range from 0 to 0.6 m/s.•Rotating arm method provides simple and in situ ...calibration.•The proposed method is superior to other techniques for water-based applications.
An instrument for calibration of hot-wire probes at very low velocities in water applications is introduced. The technique is based on moving a hot-wire probe by means of a rotating-arm device in still water. This simple in situ calibration method is principally beneficial for the investigations of three-dimensional boundary layers which are encountered for instance over rotating disks. In addition to this proposed technique, an existing alternative method in which the calibration is performed against a known reference velocity over a flat surface of a rotating disk is conducted. The comparison of both methods show that the rotating-arm technique is superior to that existing alternative flat-surface calibration method.
Spiking Neural Networks (SNNs) compute in an event-based manner to achieve a more efficient computation than standard Neural Networks. In SNNs, neuronal outputs are not encoded as real-valued ...activations but as sequences of binary spikes. The motivation of using SNNs over conventional neural networks is rooted in the special computational aspects of spike-based processing, especially the high degree of sparsity of spikes. Well-established implementations of Convolutional Neural Networks (CNNs) feature large spatial arrays of Processing Elements (PEs) that remain highly underutilized in the face of activation sparsity. We propose a novel architecture optimized for the processing of Convolutional SNNs (CSNNs) featuring a high degree of sparsity. The proposed architecture consists of an array of PEs of the size of the kernel of a convolution and an intelligent spike queue that provides a high PE utilization. A constant flow of spikes is ensured by compressing the feature maps into queues that can then be processed spike-by-spike. This compression is performed at run-time, leading to a self-timed schedule. This allows the processing time to scale with the number of spikes. Also, a novel memory organization scheme is introduced to efficiently store and retrieve the membrane potentials of the individual neurons using multiple small parallel on-chip RAMs. Each RAM is hardwired to its PE, reducing switching circuitry. We implemented the proposed architecture on an FPGA and achieved a significant speedup compared to previously proposed SNN implementations (~10 times) while needing less hardware resources and maintaining a higher energy efficiency (~15 times).
Obstructive sleep apnea (OSA) is a disease that may cause many medical conditions. Neurocognitive disorders may be triggered by OSA. In recent studies, selectively decreased gray matter tissue was ...observed in patients with OSA. We aimed to determine if there was a substantial difference in patients with extreme OSA by comparing the microstructural changes in different gray matter sub-areas with healthy controls using diffusion-weighted imaging methods.
We studied 15 diagnosed severe OSA subjects before any treatment and 32 healthy control subjects. High resolution Magnetic Resonance Imaging (MRI) T1 and T2-weighted scans were visually examined to assess any major brain lesions.
There were no statistically significant differences of age and gender between the groups.The left and right globus pallidus, putamen and thalamus values did not differ significantly between OSA and control subjects. Right putamen values was negatively correlated with Apnea Hypopnea Index (AHI), supine AHI and non-REM AHI in OSA subjects, but no correlations appeared with left putamen values. The other gray matter parameters did not show any correlations with PSG parameters. AHI, Supine AHI, Non-Supine AHI, REM and NON-REM AHI values was not show any correlation with Right and Left Putamen volume sizes.
We made a morphological comparison of various gray matter areas of OSA patients and healthy volunteers in our study. We observed a significant decrease in right putamen gray matter volumes in patients with higher AHI values. Decreased cognitive functions are found in patients with OSA. In order to demonstrate this cognitive loss in patients with morphologically there is a need for further prospective studies with larger sample sizes.
•We made a morphological comparison of various gray matter areas of OSA patients and healthy volunteers in our study. Gray matter sites are in different sizes in severe obstructive sleep apnea patients.•Right putamen values was negatively correlated with AHI, supine AHI and non-REM AHI in OSA subjects, but no correlations appeared with left putamen values.•AHI, Supine AHI, Non- Supine AHI, REM and NON-REM AHI values was not show any correlation with Right and Left Putamen volume sizes.•We observed a significant decrease in right putamen gray matter volumes in patients with higher AHI values.•In this study, a limitation to research was the number of patients with severe OSA. Besides that, measurements were performed from limited anatomical areas.
AnyHLS: High-Level Synthesis With Partial Evaluation Ozkan, M. Akif; Perard-Gayot, Arsene; Membarth, Richard ...
IEEE transactions on computer-aided design of integrated circuits and systems,
11/2020, Letnik:
39, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Field programmable gate arrays (FPGAs) excel in low power and high throughput computations, but they are challenging to program. Traditionally, developers rely on hardware description languages, such ...as Verilog or VHDL to specify the hardware behavior at the register-transfer level. High-level synthesis (HLS) raises the level of abstraction but still requires FPGA design knowledge. Programmers usually write pragma-annotated C/C++ programs to define the hardware architecture of an application. However, each hardware vendor extends its own C dialect using its own vendor-specific set of pragmas. This prevents portability across different vendors. Furthermore, pragmas are not first-class citizens in the language. This makes it hard to use them in a modular way or design proper abstractions. In this article, we present AnyHLS, an approach to synthesize FPGA designs in a modular and abstract way. AnyHLS is able to raise the abstraction level of the existing HLS tools by resorting to programming language features such as types and higher order functions as follows. It relies on partial evaluation to specialize and to optimize the user application based on a library of abstractions. Then, vendor-specific HLS code is generated for Intel and Xilinx FPGAs. Portability is obtained by avoiding any vendor-specific pragmas at the source code. In order to validate achievable gains in productivity, a library for the domain of image processing is introduced as a case study, and its synthesis results are compared with several state-of-the-art domain-specific language (DSL) approaches for this domain.
This study was aimed at the molecular characterisation of bovine papillomavirus type 1 (BPV-1) isolated from papilloma cases in the northwestern region of Turkey. BPV-1 is a widely occurring ...oncogenic virus in cattle and is associated with benign epithelial neoplasia which causes significant economic losses in dairy and beef cattle because of treatment costs. In this study, 29 suspected papilloma specimens were collected from cattle in northwestern Turkey. These samples underwent molecular characterisation via the polymerase chain reaction (PCR) and sequencing analysis as well as macroscopic and histopathological examination. The histopathological examinations confirmed papilloma as the main lesion type in the specimens. Of the 29 papilloma-like tissue samples that were collected, 11 (i.e. 37.93%) were detected as positive and determined as containing BPV-1 (11 of 11, 100%). Using a partial sequence for the L1 gene acquired from GenBank, phylogenetic analysis confirmed the presence of BPV-1 and revealed that the infection might have originated in cross bred domestic and imported cattle. This study provides potentially useful information on the origin and spread of this disease. Its results can potentially aid in the development of appropriate control measures and therapeutic or vaccination strategies against the BPV-1 strain of bovine papillomatosis.
The main objective of this study is to assess the effectiveness of attached permeable plates in suppressing nominally two-dimensional vortex shedding from a fixed cylinder. The permeable plate along ...the entire span of the cylinder was made of a chrome-nickel screen and was attached normal to the cylinder surface. The main parameters of the study are porosity of the permeable plate, β, and the plate angle of the cylinder-plate arrangement, θ, with respect to the freestream. Experiments were performed using Particle Image Velocimetry (PIV) and Flow Visualization Techniques. Additionally, drag force measurements were carried out in a wind tunnel to analyze the effects of permeable plates on drag coefficient of the circular cylinder. The results revealed that the use of a permeable plate successfully suppresses the vortex shedding downstream of the circular cylinder by reducing the velocity fluctuations in the wake, elongating the vortex formation region further downstream and attenuating the vortex shedding frequency. The porosity values of β=0.4 and 0.5 with plate angles in the range of 35°≤θ≤90° were found to be effective on suppressing the vortex shedding. Furthermore, both the drag coefficients of the cylinder-plate arrangement and the max were reduced almost for all porosity ratios for θ<30°.
•An alternative passive flow control device was introduced in this study.•Vortex shedding suppression by permeable plates was experimentally investigated.•Vortex shedding and Karman Vortex Street were eliminated by the applied method.•Fluctuations were dramatically reduced in the cylinder wake.•Drag force exerted on the cylinder was decreased compared with the plain cylinder.
•2D2C PIV measurements of a NACA0012 airfoil wake were performed at low Reynolds number under full stall condition.•The unsteady flow structure was controlled by fixed trailing-edge plates for the ...first time.•The effective plate lengths on controlling the flow were reported.•Turbulent structures were decreased in size and turbulent fluctuations were reduced.•The vortex shedding frequency was attenuated in the near wake of the airfoil.
This work aims to control the unsteady flow structure of a NACA0012 under full stall by limiting the vortex roll-up from its trailing edge. In this regard, plates with varying lengths at zero incidences were attached at the trailing edge of the airfoil at an angle of attack of α = 16° and low Reynolds number of Rec = 2.0 × 104. Under these conditions, the flow separates near the leading edge and rolls up (without reattachment) into the wake with a subsequent supercritical mode vortex shedding corresponding to the full stall condition. Planar PIV measurements were performed in a closed-loop water channel to analyze the effect of plate length on the wake characteristics of the airfoil. Turbulent flow structures of baseline airfoil and airfoil with various plate lengths (l /c = 0.1, 0.2, 0.3) were revealed and elaborated with time-averaged turbulent statistics, two-point correlations, spectral analysis, and instantaneous vorticity contours. According to the results, vortex roll-up from the trailing edge and corresponding turbulent structures were partially suppressed by the use of plates with l/c = 0.2 and l/c = 0.3 by elongating the vortex formation length. Besides, two-point correlations of fluctuating velocity components revealed that the use of trailing edge plates of l/c > 0.1 is effective in decreasing the size and magnitude of turbulent structures. Consequently, the turbulent fluctuations were found to be reduced, and the vortex shedding frequency was attenuated in the near wake of the airfoil.
•Ground borne vibrations generated by heavy vehicles were measured.•Design considerations for foundation of a high-precision instrument were evaluated.•Constructing a pile foundation system was ...recommended.•Measurements showed that springs with wire mesh might be a feasible application.•Surge frequencies of helical coil springs should be taken into consideration.
This study focuses on the foundation design and vibration isolation of a high-precision instrument subjected to ground-borne vibrations. The allowable vibration level for the proper operation of the sensitive equipment was 50μg in a frequency range of 1–300Hz. Prior to foundation design, first, an extensive field survey including geological and geophysical tests were performed in situ to obtain the static and dynamic physical properties of the soils. Next, vibration levels at various locations in the vicinity of moving vibration sources at the site were measured by accelerometers in one third octave frequency range from 1Hz to 1000Hz. Background vibration levels at the site were also measured while all of the vibration sources were inactive. Based on the measurements, a special foundation system was designed to reduce the vibration levels at the base of the precision instrument to allowable vibration limits while the vibration sources were active. Consequently, measurements were performed on the actual true scale foundation structure constructed at the site to assess the vibration isolation performance of specially designed structure. The actual vibration levels on top of the inertia mass show good agreement with the predicted values.
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