A PubMed query run in June 2018 using the keyword 'blockchain' retrieved 40 indexed papers, a reflection of the growing interest in blockchain among the medical and healthcare research and practice ...communities. Blockchain's foundations of decentralisation, cryptographic security and immutability make it a strong contender in reshaping the healthcare landscape worldwide. Blockchain solutions are currently being explored for: (1) securing patient and provider identities; (2) managing pharmaceutical and medical device supply chains; (3) clinical research and data monetisation; (4) medical fraud detection; (5) public health surveillance; (6) enabling truly public and open geo-tagged data; (7) powering many Internet of Things-connected autonomous devices, wearables, drones and vehicles, via the distributed peer-to-peer apps they run, to deliver the full vision of smart healthy cities and regions; and (8) blockchain-enabled augmented reality in crisis mapping and recovery scenarios, including mechanisms for validating, crediting and rewarding crowdsourced geo-tagged data, among other emerging use cases. Geospatially-enabled blockchain solutions exist today that use a crypto-spatial coordinate system to add an immutable spatial context that regular blockchains lack. These geospatial blockchains do not just record an entry's specific time, but also require and validate its associated proof of location, allowing accurate spatiotemporal mapping of physical world events. Blockchain and distributed ledger technology face similar challenges as any other technology threatening to disintermediate legacy processes and commercial interests, namely the challenges of blockchain interoperability, security and privacy, as well as the need to find suitable and sustainable business models of implementation. Nevertheless, we expect blockchain technologies to get increasingly powerful and robust, as they become coupled with artificial intelligence (AI) in various real-word healthcare solutions involving AI-mediated data exchange on blockchains.
Estimating vehicles’ locations is one of the key components in intelligent traffic management systems (ITMSs) for increasing traffic scene awareness. Traditionally, stationary sensors have been ...employed in this regard. The development of advanced sensing and communication technologies on modern vehicles (MVs) makes it feasible to use such vehicles as mobile sensors to estimate the traffic data of observed vehicles. This study aims to explore the capabilities of a monocular camera mounted on an MV in order to estimate the geolocation of the observed vehicle in a global positioning system (GPS) coordinate system. We proposed a new methodology by integrating deep learning, image processing, and geometric computation to address the observed-vehicle localization problem. To evaluate our proposed methodology, we developed new algorithms and tested them using real-world traffic data. The results indicated that our proposed methodology and algorithms could effectively estimate the observed vehicle’s latitude and longitude dynamically.
The present article deals with the study of special flows such as circulatory, radial, and spiral flows, respectively, for the magnetohydrodynamics system with the van der Waals fluid. Employing the ...method of hodograph transformation, the solutions have been obtained in the (u,v)-plane. An inversion of the spiral solution back to the (x,y)-plane is possible under a specific requirement, i.e.,bˆ2>2aρ, where bˆ represents Alfven speed and a is the van der Waals parameter.
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The mutation, crossover, and selection of CPI-DE.
•Due to the fact that single population fails to contain enough information to estimate the covariance matrix reliably, this paper ...updates the covariance matrix in DE by an adaptation procedure, which makes use of the cumulative distribution information of the population.•CPI-DE provides a simple yet efficient synergy of two kinds of crossover: the crossover in the Eigen coordinate system and the crossover in the original coordinate system. The former aims at identifying the properties of the fitness landscape and improving the efficiency and effectiveness of DE by producing the offspring toward promising directions. In addition, the purpose of the latter is to maintain the superiority of the original DE. Moreover, no extra parameters are required in CPI-DE.•Our experimental studies have shown that CPI-DE is capable of enhancing the performance of several classic DE versions and advanced DE variants.
Differential evolution (DE) is one of the most popular paradigms of evolutionary algorithms. In general, DE does not exploit distribution information provided by the population and, as a result, its search performance is limited. In this paper, cumulative population distribution information of DE has been utilized to establish an Eigen coordinate system by making use of covariance matrix adaptation. The crossover operator of DE implemented in the Eigen coordinate system has the capability to identify the features of the fitness landscape. Furthermore, we propose a cumulative population distribution information based DE framework called CPI-DE. In CPI-DE, for each target vector, two trial vectors are generated based on both the original coordinate system and the Eigen coordinate system. Then, the target vector is compared with these two trial vectors and the best one will survive into the next generation. CPI-DE has been applied to two classic versions of DE and three state-of-the-art variants of DE for solving two sets of benchmark test functions, namely, 28 test functions with 30 and 50 dimensions at the 2013 IEEE Congress on Evolutionary Computation, and 30 test functions with 30 and 50 dimensions at the 2014 IEEE Congress on Evolutionary Computation. The experimental results suggest that CPI-DE is an effective framework to enhance the performance of DE.
Due to the lack of structure and part information in non-cooperative targets, the task of pose estimation suffers from unstable and unreliable initial coordinate system. In this paper, we introduce a ...curve-skeleton-based method to construct the robust coordinate system automatically for non-cooperative targets. First, a nonmanifold-Laplacian-based method is proposed to extract the curve skeleton from point clouds. The proposed method solves the over-contraction problem while preserves the topology and structure of skeleton well during point clouds contraction. Additionally, we create the skeleton graph to detect the skeleton structure and key points automatically. Then, the detected skeleton feature is used to construct target coordinate system, and improve the stability and robustness. Specifically, a real-scan dataset is constructed in this paper, and the proposed point cloud contraction method outperforms previous methods in structural representation and visualization. The mean rotation error of proposed coordinate system construct method performs 0.1249° and 1.2135° in 0%–30% noise ratio of distortions and outliers, and performs 7.04° and 4.21° in real-scan aircraft and satellite datasets. The results in complete and incomplete datasets verify the robustness and reliability of our skeleton-based coordinate system.
•We introduce the local contraction state and solve the over-shrinkage.•We construct the skeleton-based coordinate system for non-cooperative targets.
This letter proposes a simplified modulation strategy for the open-end winding permanent-magnet synchronous motor (OW-PMSM) system with common dc bus under the open-phase fault condition, with the ...suppression of the circulating current. Based on the analysis of the voltage distribution of the OW-PMSM under the open-phase fault, a phase-shifted stationary coordinate system is proposed and applied to synthesize the reference voltage. In the proposed modulation process, the duration time of the two selected orthogonal voltage vectors is directly obtained and both sector identification and calculation of trigonometric function can be avoided. Furthermore, the arrangement of switching signals is achieved universally according to the switching states of the selected voltage vectors. Thus, the proposed modulation scheme can be greatly simplified, compared with the conventional strategies. Moreover, the current controller with low bandwidth is applied to suppress the circulating current, considering its effect on the currents in the synchronous rotating coordinate system. The performance of the proposed scheme is validated experimentally in an OW-PMSM system with a common dc bus under the open-phase fault.
No shale-rock physical model has been established in the observation coordinate system. To this end, this paper carried out anisotropic wave velocity tests on shale rock and compared the Thomsen, ...Daley, and Berryman solutions to characterize anisotropic acoustic wave velocity. Finally, the Daley solution was selected. Based on basic rock physical models, such as SCA and DEM methods, and combined with the Daley solution, an anisotropic shalerock physical model was established in the observation coordinate system and applied in Well B1 in the Luzhou area, Sichuan Basin. Our research conclusions were as follows: 1. for the samples from the same core, the P-wave velocities in three directions were in the order
V
P11
>
V
P45
>
V
P33
, shear-wave velocity
V
S11
was the largest, but
V
S33
and
V
S45
did not follow the law of
V
s33
>
V
s45
for some samples; 2. the Daley solution, which not only considers the accuracy requirements but also has a complete expression of P-, SV-, and SH-waves, is most suitable for characterization of anisotropic wave velocity in this study area; 3. the rock physical model constructed in the observation coordinate system has high accuracy, in which the absolute value of the relative error of the P-wave slowness was between 0% and 5.05% (0.55% on average), and that of shear-wave slowness was between 0% and 6.05% (0.59% on average); 4. the acoustic waves recorded in Well B1 in the observation coordinate system were very different from those in the constitutive coordinate system. The relative difference of the P-wave was between 6.76% and 30.84% (14.68% on average), and that of the S-wave was between 7.00% and 23.44% (13.99% on average). The acoustic slowness measured in the observation coordinate system, such as in a deviated well or a horizontal well section, must be converted to the constitutive coordinate system before it can be used in subsequent engineering applications; 5. the anisotropic shale-rock physical model built in the observation coordinate system proposed in this paper can provide basic data and guidance for subsequent pore pressure prediction, geomechanical modeling, and fracturing stimulation design for deviated and horizontal wells.
Fiber-Optical Analog of the Event Horizon Philbin, Thomas G; Kuklewicz, Chris; Robertson, Scott ...
Science (American Association for the Advancement of Science),
03/2008, Letnik:
319, Številka:
5868
Journal Article
Recenzirano
Odprti dostop
The physics at the event horizon resembles the behavior of waves in moving media. Horizons are formed where the local speed of the medium exceeds the wave velocity. We used ultrashort pulses in ...microstructured optical fibers to demonstrate the formation of an artificial event horizon in optics. We observed a classical optical effect: the blue-shifting of light at a white-hole horizon. We also showed by theoretical calculations that such a system is capable of probing the quantum effects of horizons, in particular Hawking radiation.
Three-phase four-leg voltage-source inverter (FL-VSI) has the advantages of flexible control and high power density. For FL-VSI with three-phase asymmetric loads, positive-sequence and ...negative-sequence synchronous rotating dq-based PI controllers are usually applied to realize balanced three-phase output voltages. However, symmetric component decomposition and positive-sequence and negative-sequence rotating coordinate transformation make the digital implementation of the control system complicated. To mitigate voltage unbalance rate (VUR) and to avoid the transformation of rotating coordinates and the calculation of symmetric component decomposition, a hybrid pulse train (PT) control strategy for stand-alone FL-VSI with a three-phase asymmetric load in <inline-formula> <tex-math notation="LaTeX">\alpha \beta z </tex-math></inline-formula> stationary coordinate system is proposed. The PT control strategy in <inline-formula> <tex-math notation="LaTeX">\alpha \beta </tex-math></inline-formula> stationary coordinate system is utilized to mitigate negative-sequence VUR, and the zero-sequence differential feedforward strategy in the <inline-formula> <tex-math notation="LaTeX">z </tex-math></inline-formula> stationary coordinate system is applied to mitigate zero-sequence VUR. The simulation and experimental results of the proposed control schemes are provided, which show that the VUR of the proposed system is mitigated below 2%, which meets IEC Standards.
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