782 research outputs found
A novel geometric key-frame selection method for visul-inertial slam and odometry systems
No full textGiven the importance of key-frame selection in determining the positioning accuracy of Simultaneous Localization And Mapping (SLAM) and Odometry algorithms, and the urgent need in this field for a flexible key-frame selection algorithm, this paper proposes a novel and geometric method for key-frame selection built on top of ORB-SLAM3. It takes a key-frame in a completely robust and flexible way regardless of the environment, data and scene conditions, and according to the physics and geometry of the environment. In the proposed method, the camera sensor and IMU take key-frames simultaneously and in parallel. While selecting a key-frame, an adaptive threshold first decides whether the geometric condition of the frame is appropriate based on the degree of change in the orientation of the point visibility vector from the last key-frame to the current frame. Then the quality of the frame is evaluated by examining the distribution of points inside the frame by a balance criterion. A new key-frame will be created if both conditions provide a positive answer. In addition, if the IMU sensor detects large changes in acceleration, a key-frame independently chosen. The proposed method is evaluated qualitatively and quantitatively on the EuRoC dataset by comparing the algorithm trajectory to a reference trajectory and usig the Absolute Trajectory Error (ATE) and the processing time as metrics. The evaluation results indicate a 26% improvement in the positioning of the algorithm although it has a 9% increase in the processing time due to its geometric key-frame selection process
Expression analysis of protein inhibitor of activated STAT (PIAS) genes in IFNβ-treated multiple sclerosis patients [Corrigendum]
No full textTaheri M, Azimi G, Sayad A, et al. J Inflamm Res. 2018;11:457–463.On page 457, Author list and Correspondence, the last author’s name was misspelt. The correct name is Soudeh Ghafouri-Fard.Read the original articl
Electrical and mechanical stability of flexible, organic electrolyte-gated transistors based on iongel and hydrogels
Get PDFElectrolyte-gated transistors (EGTs) have been widely investigated for applications in bioelectronics owing to their low operating voltage and mixed ionic-electronic conduction. The ion-gating media play a primary role in determining the operating voltage and electrical stability of these devices. In this study, we employed an iongel based on an ionic liquid and hydrogels based on polyvinyl alcohol (PVA) as the gating media for EGTs using the organic semiconductor poly(N-alkyldiketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene) (DPP-DTT) as the channel material. The device characteristics revealed that iongel-gated transistors showed superior electrical stability over hydrogel-gated transistors, because hydrogels undergo dehydration over time. After 65 cycles of pulse measurements, the drain current of the iongel-gated devices did not show any significant change, whereas it decreased to similar to 50% of the initial value for the hydrogel-gated devices. By adding glycerol as an anti-dehydrating agent, the current decreased by only similar to 10% under the same conditions, demonstrating improved operational stability. Finally, we fabricated flexible EGTs on polyethylene terephthalate (PET), which can be operated under different bending radii
FIGURE 2. Basiria khouzestanensis n in Description of Basiria khouzestanensis n. sp. (Nematoda: Tylenchidae) from Iran and its phylogenetic relationships with other species in the family
No full textFIGURE 2. Basiria khouzestanensis n. sp. A&B: Female pharyngeal region, C: Lateral field at mid-body, D: Female reproductive system, E&F: Female tail, G&H: Male tail. (Scale bars = 20 µm.)Published as part of Eisvand, Payam, Nejad, Reza Farrokhi & Azimi, Sedighe, 2019, Description of Basiria khouzestanensis n. sp. (Nematoda: Tylenchidae) from Iran and its phylogenetic relationships with other species in the family, pp. 482-490 in Zootaxa 4563 (3) on page 486, DOI: 10.11646/zootaxa.4563.3.4, http://zenodo.org/record/260141
Analysis and Mitigation of Soft-Errors on High Performance Embedded GPUs
Get PDFMultiprocessor system-on-chip such as embedded GPUs are becoming very popular in safety-critical applications,
such as autonomous and semi-autonomous vehicles. However, these devices can suffer from the effects of soft-errors, such as those produced by radiation effects. These effects are able to generate unpredictable misbehaviors. Fault tolerance oriented to multi-threaded software introduces severe performance degradations due to the redundancy, voting and correction threads operations. In this paper, we propose a new fault injection environment for NVIDIA GPGPU devices and a fault tolerance approach based on error detection and correction threads executed during data transfer operations on embedded GPUs. The fault injection environment is capable of automatically injecting faults into the instructions at SASS level by instrumenting the CUDA binary executable file. The mitigation approach is based on concurrent error detection threads running simultaneously with the memory stream device to host data transfer operations. With
several benchmark applications, we evaluate the impact of softerrors classifying Silent Data Corruption, Detection,
Unrecoverable Error and Hang. Finally, the proposed mitigation approach has been validated by soft-error fault injection
campaigns on an NVIDIA Pascal Architecture GPU controlled by Quad-Core A57 ARM processor (JETSON TX2) demonstrating an advantage of more than 37% with respect to state of the art solution
Recent advances of polymer-based piezoelectric composites for biomedical applications
No full textOver the past decades, electronics have become central to many aspects of biomedicine and wearable device technologies as a promising personalized healthcare platform. Lead-free piezoelectric materials for converting mechanical into electrical energy through piezoelectric transduction are of significant value in a diverse range of technological applications. Organic piezoelectric biomaterials have attracted widespread attention as the functional materials in the biomedical devices due to their advantages of excellent biocompatibility. They include synthetic and biological polymers. Many biopolymers have been discovered to possess piezoelectricity in an appreciable amount, however their investigation is still preliminary. Due to their piezoelectric properties, better known synthetic fluorinated polymers have been intensively investigated and applied in biomedical applications including controlled drug delivery systems, tissue engineering, microfluidic and artificial muscle actuators, among others. Piezoelectric polymers, especially poly (vinylidene fluoride) (PVDF) and its copolymers are increasingly receiving interest as smart biomaterials due to their ability to convert physiological movements to electrical signals when in a controllable and reproducible manner. Despite possessing the greatest piezoelectric coefficients among all piezoelectric polymers, it is often desirable to increase the electrical outputs. The most promising routes toward significant improvements in the piezoelectric response and energy-harvesting performance of such materials is loading them with various inorganic nanofillers and/or applying some modification during the fabrication process. This paper offers a comprehensive review of the principles, properties, and applications of organic piezoelectric biomaterials (polymers and polymer/ceramic composites) with special attention on PVDF-based polymers and their composites in sensors, drug delivery and tissue engineering. Subsequently focuses on the most common fabrication routes to produce piezoelectric scaffolds, tissue and sensors which is electrospinning process. Promising upcoming strategies and new piezoelectric materials and fabrication techniques for these applications are presented to enable a future integration among these applications
The application of a stockpile stochastic model into long-term open pit mine production scheduling to improve the feed grade for the processing plant
Get PDFThis paper presents a chance-constrained integer programming approach based on the linear method to solve the long-term open pit mine production scheduling problem. Specifically, a single stockpile has been addressed for storing excess low-grade material based on the availability of processing capacity and for possible future processing. The proposed scheduling model maximizes the project NPV while respecting a series of physical and economic constraints. Differently from common practice, where deterministic models are used to calculate the average grade for material in the stockpiles, in this work a stochastic approach was performed, starting from the time of planning before the stockpile realization. By performing a probability analysis on two case studies (on iron and gold deposits), it was proven that the stockpile attributes can be treated as normally distributed random variables. Afterwards, the stochastic programming model was formulated in an open pit gold mine in order to determine the optimum amount of ore dispatched from different bench levels in the open pit and at the same time a low-grade stockpile to the mill. The chance-constrained programming was finally applied to obtain the equivalent deterministic solution of the primary model. The obtained results have shown a better feed grade for the processing plant with a higher NPV and probability of grade blending constraint satisfaction, with respect to using the traditional stockpile deterministic model.
Four‐dimensional (Bio‐)printing: A review on stimuli‐responsive mechanisms and their biomedical suitability
Get PDFThe applications of tissue engineered constructs have witnessed great advances in the last few years, as advanced fabrication techniques have enabled promising approaches to develop structures and devices for biomedical uses. (Bio‐)printing, including both plain material and cell/material printing, offers remarkable advantages and versatility to produce multilateral and cell-laden tissue constructs; however, it has often revealed to be insufficient to fulfill clinical needs. Indeed, three‐dimensional (3D) (bio‐)printing does not provide one critical element, fundamental to mimic native live tissues, i.e., the ability to change shape/properties with time to respond to microenvironmental stimuli in a personalized manner. This capability is in charge of the so‐called “smart materials”; thus, 3D (bio‐)printing these biomaterials is a possible way to reach four-dimensional (4D) (bio‐)printing. We present a comprehensive review on stimuli‐responsive materials to produce scaffolds and constructs via additive manufacturing techniques, aiming to obtain constructs that closely mimic the dynamics of native tissues. Our work deploys the advantages and drawbacks of the mechanisms used to produce stimuli‐responsive constructs, using a classification based on the target stimulus: humidity, temperature, electricity, magnetism, light, pH, among others. A deep understanding of biomaterial properties, the scaffolding technologies, and the implant site microenvironment would help the design of innovative devices suitable and valuable for many biomedical applications
Design of Experiment Based Prediction of Passivity Breakdown Potential for 304L Stainless Steel
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