The rapid growth of remote sensing big data (RSBD) has attracted considerable attention from both academia and industry. Despite the progress of computer technologies, conventional computing ...implementations have become technically inefficient for processing RSBD. Cloud computing is effective in activating and mining large-scale heterogeneous data and has been widely applied to RSBD over the past years. This study performs a technical review of cloud-based RSBD storage and computing from an interdisciplinary viewpoint of remote sensing and computer science. First, we elaborate on four critical technical challenges resulting from the scale expansion of RSBD applications, i.e. raster storage, metadata management, data homogeneity, and computing paradigms. Second, we introduce state-of-the-art cloud-based data management technologies for RSBD storage. The unit for manipulating remote sensing data has evolved due to the scale expansion and use of novel technologies, which we name the RSBD data model. Four data models are suggested, i.e. scenes, ARD, data cubes, and composite layers. Third, we summarize recent research on the application of various cloud-based parallel computing technologies to RSBD computing implementations. Finally, we categorize the architectures of mainstream RSBD platforms. This research provides a comprehensive review of the fundamental issues of RSBD for computing experts and remote sensing researchers.
This paper proposes a new LLC resonant DC-DC topology with bidirectional power flow capability. All the switches in the proposed topology can achieve zero voltage switching (ZVS) at turn on, and zero ...current switching (ZCS) is achieved for the output side switches at turn off. Compared with the traditional bidirectional dual active bridge (DAB) converter, the turn off current is greatly reduced, and the frequency modulation control scheme can almost eliminate the large circulating energy. Therefore, the conversion efficiency can be much improved, which makes it quite attractive in energy storage applications. The output characteristic of the proposed LLC converter is different from the conventional unidirectional LLC resonant converter. A new analytical model is also proposed in this paper. The detailed operating principle and performance of the proposed topology are analyzed. And a 1 kW prototype is built to verify the theoretical analysis. Over 98% efficiency is achieved base on the prototype.
This paper proposes an improved bidirectional LLC resonant topology with a new control scheme. All the switches in the proposed topology can achieve soft switching. Compared with traditional isolated ...bidirectional dc-dc converters such as dual active bridge converter, the reverse energy and turn-off loss are reduced dramatically, and the conversion efficiency can be much improved. With the proposed new control scheme, the power flow direction and output power of the proposed converter can be changed automatically and continuously, which is attractive for energy storage systems to balance the energy and to keep the dc-bus voltage constant. Performance of the proposed circuit is validated by the experimental results from a 1-kW prototype. Over 97% efficiency is achieved at full load condition based on the prototype.
This paper proposes a bidirectional three-level LLC resonant converter with a new pulse width and amplitude modulation control method. With different control signals, it has three different operation ...modes with different voltage gains. Therefore, it can achieve wide voltage gain range by switching among these three modes, which is attractive for energy storage system applications needing wide voltage variation. The proposed topology operates with constant switching frequency, which is easy to implement with digital control, and it can achieve soft switching for all the switches and diodes in the circuit as a conventional LLC resonant converter. The performance of the proposed converter is validated by the experimental results from a 1-kW prototype with 20 A maximum output current.
Flyback converter has been widely used in low power offline applications due to its simplicity and cost-effectiveness. Conventionally, the output voltage or output current are sensed and regulated by ...an isolated feedback circuit with opto-coupler. In order to further simplify the circuit and reduce the cost, primary side control for flyback converter has been adopted to eliminate the opto-coupler feedback circuit. The primary side output voltage control is quite straightforward. However, the primary side output current control is more complex than the output voltage control, which is also required for many applications like LED drivers. In this paper, a thorough review of the existing output current control methods are presented, including pulse frequency modulation (PFM), current estimation, adaptive peak current value and duty cycle control. Finally, an improved primary side output current control method based on the current estimation is studied, which is more flexible and accurate. Experimental results from a 15W LED driver prototype are presented to verify the performance of the control scheme.
This paper proposes a high efficiency low cost AC/DC converter for adapter application. In order to achieve high efficiency and low cost for adapter with universal AC input, a single stage bridgeless ...flyback PFC converter with peak current clamping technique was proposed. Compared with conventional flyback PFC converter, the conduction loss is reduced due to bridgeless structure. And the size of transformer can also be significantly reduced due to lower peak current, which results in lower cost and higher power density. Detailed operation principles and design considerations are illustrated. Experimental results from a 90W prototype with universal input and 20V/4.5A output are presented to verify the operation and performance of the proposed converter. The minimum efficiency at full load is above 91% over the entire input range.
Budesonide (BUD), a locally acting glucocorticoid with low side effects, is recommended in several Crohn's disease (CD) drug treatment guidelines as the first choice for early treatment. ...Nevertheless, the extensive first-pass effect mediated by P-glycoprotein (P-gp) and Cytochrome P450 3A4 (CYP3A4) leads to low bioavailability and limits further applications. Curcumin (CUR), a natural polyphenol derived from turmeric, has been found to influence the in vivo processes of drugs by affecting the activity of P-gp and CYP3A4. However, the pharmacokinetic interactions between BUD and CUR remains elusive, so an ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) method was established for the simultaneous determination of BUD and CUR in the tissue. The results showed that the area under the concentration-time curve 0 to time (AUC0→t) of BUD in the colon and kidney increased by approximately 32.35% and 39.03% respectively in the co-administered group compared to the single-drug group, while the small intestine, liver and plasma decreased by 80.03%, 67.34% and 24.34% respectively compared to the single-drug group. Therefore, long-term treatment with CUR can increase the concentration of BUD in the colonic area without increasing its systemic exposure, thus potentially reducing the incidence of side effects.
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•First assessment of the effect of curcumin on the tissue distribution of budesonide in vivo.•UPLC-MS/MS study to simultaneously determine budesonide and curcumin for the first time.•The study concluded that curcumin increased the drug concentration of budesonide in the colon but not in plasma.•Curcumin may be beneficial in improving budesonide treatment for colon disease.•The results of this study will provide a reference for pharmacokinetic interaction analysis of curcumin and budesonide.
The inhomogeneous fiber structure through the whole SAF2507 SDSS FSW joint and its effect on the mechanical behaviors were investigated. The results showed that the FSW-induced thermomechanical ...effect mainly led to the changes in grain size and direction of fiber structures. Despite the different refinement degree, the grains of ferrite and austenite were generally refined throughout the entire stir zone (SZ), which primarily governed by CDRX and DDRX, respectively. The weakest texture formed on the shoulder affected zone (SAZ) was mainly composed of J components in ferrite and C components in austenite, which was correlated with the longer duration at elevated temperature during FSW, resulting in the dramatic coarsening of grains in constituent phases. Inhomogeneous fiber structures with various directions relative to the initial horizontal direction were created in the different regions of SZ. In comparison to BM, the FSW joint exhibited greatly higher yield strength (YS) of ∼687 MPa, a slightly low ultimate tensile strength (UTS) of ∼889 MPa, but an obviously reduced fracture elongation of ∼17%. The higher YS could be attributed to the grain refinement, while the resultant fiber structures on the SAZ led to earlier initiation and propagation of cracks along the fiber structure with 45° direction during plastic deformation, and accelerated the fracture at the shoulder affected zone on the retreating side (RS) of FSW joint.
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•The stir zone temperature is monitored by wireless technology.•The fiber structures with various directions have formed within stir zone.•The dual-phase fiber structure formed in shoulder affected zone dominates fracture.
The dual active bridge topology is attractive in bidirectional DC-DC applications due to its simplicity and soft switching capability. However, its high circulating energy will cause high conduction ...loss. This paper proposed two new dual active bridge topologies in order to minimize the circulating energy with minimal auxiliary components. These topologies can also achieve ZVS in all load range as well as simple control scheme. These topologies will be attractive in high power high density applications like battery charger, hybrid vehicle, electric vehicle and solar power system. The detailed analysis and comparison between the proposed topologies and traditional DAB converters are also presented in the paper. The experimental and simulation results verified the theoretical analysis well.
