The -(Fe, Cr)3C pseudo-binary eutectic alloy with K, Ce, Sb additives was unidirectionally solidified in a Brigdman-type unit. The quasi-regular, lamellar eutectic carbide was changed into rods and bent blades by the modifiers under well-controlled conditions. At very slow growth, partial modification was common. At growth rates corresponding to a slightly cellular interface, a fully modified structure could be obtained. The modification behaviour as a function of the modifying element, its concentration and the growth rate is described and discussed. 相似文献
Since the first case of COVID-19 was reported in December 2019, many studies have been carried out on artificial intelligence for the rapid diagnosis of the disease to support health services. Therefore, in this study, we present a powerful approach to detect COVID-19 and COVID-19 findings from computed tomography images using pre-trained models using two different datasets. COVID-19, influenza A (H1N1) pneumonia, bacterial pneumonia and healthy lung image classes were used in the first dataset. Consolidation, crazy-paving pattern, ground-glass opacity, ground-glass opacity and consolidation, ground-glass opacity and nodule classes were used in the second dataset. The study consists of four steps. In the first two steps, distinctive features were extracted from the final layers of the pre-trained ShuffleNet, GoogLeNet and MobileNetV2 models trained with the datasets. In the next steps, the most relevant features were selected from the models using the Sine–Cosine optimization algorithm. Then, the hyperparameters of the Support Vector Machines were optimized with the Bayesian optimization algorithm and used to reclassify the feature subset that achieved the highest accuracy in the third step. The overall accuracy obtained for the first and second datasets is 99.46% and 99.82%, respectively. Finally, the performance of the results visualized with Occlusion Sensitivity Maps was compared with Gradient-weighted class activation mapping. The approach proposed in this paper outperformed other methods in detecting COVID-19 from multiclass viral pneumonia. Moreover, detecting the stages of COVID-19 in the lungs was an innovative and successful approach. 相似文献
Unmanned aerial vehicles have been widely used in many areas of life. They communicate with each other or infrastructure to provide ubiquitous coverage or assist cellular and sensor networks. They construct flying ad hoc networks. One of the most significant problems in such networks is communication among them over a shared medium. Using random channel access techniques is a useful solution. Another important problem is that the variations in the density of these networks impact the quality of service and introduce many challenges. This paper presents a novel density-aware technique for flying ad hoc networks. We propose Density-aware Slotted ALOHA Protocol that utilizes slotted ALOHA with a dynamic random access probability determined using network density in a distributed fashion. Compared to the literature, this paper concentrates on proposing a three-dimensional, easily traceable model and stabilize the channel utilization performance of slotted ALOHA with an optimized channel access probability to its maximum theoretical level, 1/e, where e is the Euler’s number. Monte-Carlo simulation results validate the proposed approach leveraging aggregate interference density estimator under the simple path-loss model. We compare our protocol with two existing protocols, which are Slotted ALOHA and Stabilized Slotted ALOHA. Comparison results show that the proposed protocol has 36.78% channel utilization performance; on the other hand, the other protocols have 24.74% and 30.32% channel utilization performances, respectively. Considering the stable results and accuracy, this model is practicable in highly dynamic networks even if the network is sparse or dense under higher mobility and reasonable non-uniform deployments.
Most of the published literature on robust design is basically concerned with a single response. However, the reality is that common industrial problems usually involve several quality characteristics, which are often correlated. Traditional approaches to multidimensional quality do not offer much information on how much better or worse a process is when finding optimal settings. Köksoy and Fan [Engineering Optimization 44 (8): 935–945] pointed out that the upside-down normal loss function provides a more reasonable risk assessment to the losses of being off-target in product engineering research. However, they only consider the single-response case. This article generalizes their idea to more than one response under possible correlations and co-movement effects of responses on the process loss. The response surface methodology has been adapted, estimating the expected multivariate upside-down normal loss function of a multidimensional system to find the optimal control factor settings of a given problem. The procedure and its merits are illustrated through an example. 相似文献
Abstract: In this study, an automatic three-dimensional computer-aided detection system for colonic polyps was developed. Computer-aided detection for computed tomography colonography aims at facilitating the detection of colonic polyps. First, the colon regions of whole computed tomography images were carefully segmented to reduce computational burden and prevent false positive detection. In this process, the colon regions were extracted by using a cellular neural network and then the regions of interest were determined. In order to improve the segmentation performance of the study, weights in the cellular neural network were calculated by three heuristic optimization techniques, namely genetic algorithm, differential evaluation and artificial immune system. Afterwards, a three-dimensional polyp template model was constructed to detect polyps on the segmented regions of interest. At the end of the template matching process, the volumes geometrically similar to the template were emhanced. 相似文献
A range of potentially bioactive ceramic coatings, based on combinations of either hydroxyapatite (HA) or titanium oxide nanoparticles with carbon nanotubes (CNTs), have been deposited on metallic substrates, using electrophoretic deposition (EPD). Sol–gel derived, ultrafine HA powders (10–70 nm) were dispersed in multi-wall nanotube-containing ethanol suspensions maintained at pH = ∼3.5 and successfully coated onto Ti alloy wires at 20 V for 1–3 min For TiO2/CNT coatings, commercially available titania nanopowders and surface-treated CNTs in aqueous suspensions were co-deposited on stainless steel planar substrates. A field strength of 20 V/cm and deposition time of 4 min were used working at pH = 5. Although the co-deposition mechanism was not investigated in detail, the evidence suggests that co-deposition occurs due to the opposite signs of the surface charges (zeta potentials) of the particles, at the working pH. Electrostatic attraction between CNTs and TiO2 particles leads to the creation of composite particles in suspension, consisting of TiO2 particles homogenously attached onto the surface of individual CNTs. Under the applied electric field, these net negatively charged “composite TiO2/CNT” elements migrate to and deposit on the anode (working electrode). The process of EPD at constant voltage conditions was optimised in both systems to achieve homogeneous and reasonably adhered deposits of varying thicknesses on the metallic substrates.相似文献
In this simulation work, we use COSMOS logic devices—a novel single gate CMOS architecture recently announced [1]—in multi-input
logic gates, assessing its performance in terms of power·delay product. We consider three different multi-input logic circuits:
a two-input NOR gate, a three-input NOR gate, and a three-input composite NOR/NAND (NORAND) gate. For this power·delay analysis,
the transient TCAD simulations are employed in a mixed-mode approach where circuit and device simulations are coupled together,
culminating in the delay response of the circuits as well as the static/dynamic current components. The analysis shows that
all circuits, except the 3-input NOR gate, has acceptable characteristics at low-power applications and static leakage limits
all COSMOS circuits at high-bias conditions. 相似文献
Clays such as kaolinite and bentonite are widely used in various industries as sorbents. The sorptive characteristics of clays are exploited when they are used in contaminant barrier systems. To use clays effectively, their surface characteristics need to be known; especially, when they are used for contaminant sorption. Available surface area of clay minerals and the characteristics that depend on it are very sensitive to environmental changes such as those that can be induced by changes in the composition of pore fluid. Flow microcalorimetry with a down-stream concentration was used to determine the heats and amounts of adsorption of acids and bases on the clays. Test results presented herein revealed that both kaolinite and bentonite exhibit significantly different adsorption isotherms and heat of wetting under high pH and low pH conditions. Kaolinite has the capacity to adsorb both acidic and basic molecules almost equally. However, it has a tendency to adsorb more base than acid because of its stronger complexation capacity with acids than with bases. On the other hand, bentonite has a tendency to adsorb more acidic than basic molecules per gram. These results also indicate that both kaolinite and bentonite have different heats of wetting characteristics. As the concentrations of the acids and bases increase, the heat of wetting of kaolinite decreases while that of bentonite increases. 相似文献