- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Remote sensing quantifies widespread abundance of permafrost region disturbances across the Arctic and Subarctic
摘要： Local observations indicate that climate change and shifting disturbance regimes are causing permafrost degradation. However, the occurrence and distribution of permafrost region disturbances (PRDs) remain poorly resolved across the Arctic and Subarctic. Here we quantify the abundance and distribution of three primary PRDs using time-series analysis of 30-m resolution Landsat imagery from 1999 to 2014. Our dataset spans four continental-scale transects in North America and Eurasia, covering ~10% of the permafrost region. Lake area loss (?1.45%) dominated the study domain with enhanced losses occurring at the boundary between discontinuous and continuous permafrost regions. Fires were the most extensive PRD across boreal regions (6.59%), but in tundra regions (0.63%) limited to Alaska. Retrogressive thaw slumps were abundant but highly localized (<10?5%). Our analysis synergizes the global-scale importance of PRDs. The findings highlight the need to include PRDs in next-generation land surface models to project the permafrost carbon feedback.
关键词： permafrost,disturbances,Subarctic,fires,remote sensing,lakes,retrogressive thaw slumps,Arctic
更新于2025-09-23 15:23:52
-
[IEEE 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Iasi, Romania (2018.10.18-2018.10.19)] 2018 International Conference and Exposition on Electrical And Power Engineering (EPE) - Aspects Regarding Disturbances Produced by Fluorescent Tubes
摘要： This paper has a strong applicative character. There is presented a modern system for monitoring dynamic states, carried out with the help of a data acquisition board. It is insisted upon an original monitoring program conceived by the paper team. There are presented then two applications of using this system: a) (experimental) analysis of disturbances produced by a fluorescent tube; b) analysis of disturbances produced by a LED tube. A special attention is paid to the experimental aspects which emphasize the waveforms of the currents corresponding to some fluorescent tubes (in a few representative operation states). Finally, there are presented conclusions, which have been obtained by finalizing the research and the afferent bibliography.
关键词： LED tube,harmonic analysis,test,fluorescent tube,disturbances
更新于2025-09-23 15:22:29
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - High Precision Control of an Inertially Stabilized Platform for Aerial Remote Sensing Applications
摘要： Inertially stabilized platform (ISP) is an important component of the aerial remote sensing system, which is used to make the imaging sensors stable so as to obtain the high quality images by disturbance rejection. To improve the stabilization accuracy of an ISP under multi-source disturbance environment, an active disturbance rejection control (ADRC) control scheme is prosed, which is composed of three components, i.e., a tracking differentiator (TD), a nonlinear state error feedback (NLSEF) and an extended state observer (ESO). To verify the method, the experiments are carried out. The results show that the proposed method can improve the stabilization accuracy due to significant ability in disturbances rejection.
关键词： Inertially stabilized platform,empirical method,active disturbance rejection control,disturbances rejection
更新于2025-09-23 15:22:29
-
[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - The Action of Ultra-Short Super-Powerful Radio Pulses on the Earth's Atmosphere and Ionosphere
摘要： Numerical simulations of disturbances in the electron temperature and density arising from the action of ultra-short super-powerful radio pulses with different durations and powers on the Earth's atmosphere and ionosphere are presented. It is demonstrated that the electron density in the 30–60 km altitude range can be increased by 12 orders of magnitude, while the electron temperature shows an increase of the order of 10 to 100 times. The pulse durations and powers needed to create artificial ionized layers have been estimated.
关键词： ultra-short radio pulse,disturbances,numerical simulation,atmosphere,electron temperature,ionosphere,super-powerful radio pulse,electron density
更新于2025-09-23 15:21:21
-
Effect of photobiomodulation on recovery from neurosensory disturbances after sagittal split ramus osteotomy: a triple-blind randomised controlled trial
摘要： We have investigated the effect of photobiomodulation on the recovery of neurosensory function of the lip and chin after bilateral sagittal split osteotomy (BSSO). Laser irradiation was applied with a GaAs diode laser (continuous wave 980 nm wavelength, power 100 mW, and energy density 12 J/cm2). It was maintained within a 0.5 cm2 area in a total of 12 points for 60 seconds at each visit on each point. Unilateral extraoral contact photobiomodulation treatment was applied the day before operation and then on days 1, 3, 7, 14, 21, and 28 postoperatively. One side of the mandible was the intervention side and the other the control side. On the control side, the laser probe was turned off and placed on the chosen area. Neurosensory evaluations were made before and immediately after operation, and 30 days and 60 days postoperatively. Twenty-five patients were screened, and 18 who met the inclusion criteria were included in the study; 14 were women and the mean (SD) age was 23 (5) years. Analysis of the visual analogue scales for general sensibility, pain discrimination, directional discrimination, and 2-point discrimination showed a significant difference between the intervention and control sides after 30 days (p = 0.0011, 0.0034, 0.0023, and 0.0160, respectively). The difference was also significant after 60 days (p = 0.0001, 0.0002, 0.0003, and 0.0010, respectively). The thermal discrimination rate was significantly higher in the laser group than the control group 30 days after surgery (p = 0.002), but after 60 days the difference was not significant (p = 1.000). We found no side effects from the laser radiation during the two-month follow up. The results suggest that photobiomodulation accelerated the patients’ improvement from neurosensory disturbance after BSSO.
关键词： laser therapy,BSSO,visual analogue scale,neurosensory disturbances,Low-Level Light Therapy
更新于2025-09-23 15:19:57
-
[IEEE 2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior) - Plovdiv, Bulgaria (2019.9.19-2019.9.21)] 2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior) - Considerations on disturbances in the electrical supply network caused by LEDs light projectors
摘要： In the first part of this paper, the authors present the results of the luminotechnical calculations based on the reconstruction of the photometric curves of a LEDs projector PREMIUM LUX LED 38dgr type. Thus by using the equal plane angles method, the emitted total luminous flux and the efficiency of this luminaire were determined. Then was analysed the illuminance’s distribution in the horizontal and vertical plane, at different heights and the rectangular surface illuminated by the considered luminaire. In the second part of the paper is presented the analysis of disturbances in the electrical supply network caused by this type of LEDs light projectors. In this regard the test report, provided by a harmonic and flicker analyzer, Type HAR 1000-1P (EMC Partner AG Switzerland) was used. The results of the measurements were interpreted, making observations regarding harmonic current emissions, voltage fluctuations and flicker indicators.
关键词： light projectors,LEDs lighting calculations,photometric curves,harmonic current emissions,disturbances in the electrical supply network
更新于2025-09-11 14:15:04
-
Observation of short period ionospheric disturbances using a portable digital ionosonde at Sanya
摘要： A number of ionosondes have been operated in China to detect ionospheric disturbances for many years. These ionosondes, however, are not very suitable for the short period (<15 min) disturbances due to their poor time resolutions (>5 min). During recent years, the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), together with the South Central University for Nationalities (SCUN) have been developing a portable digital ionosonde (PDI) equipped with the capability to detect and characterize small-scale/short period ionospheric disturbances, and to be quickly assembled and set up at temporary field stations for low-latitude campaign coordinated observations. The PDI uses a set of technologies (for example code multiplexing and antenna/transmitter matching) that allow it to obtain quality Doppler-ionograms at a good time resolution with small transmitting antennas. A preliminary analysis of observations by the PDI at Sanya (18.3°N, 109.6°E) shows the presence of ionospheric disturbances with periods ranging between several and tens of minutes. Interestingly, the disturbances (with different periods) were found to simultaneously occur at different F region altitudes, for example with periods of ~5 and 20 min below and above ~180 km, respectively. The absence of shorter period disturbance at higher altitude is consistent with acoustic gravity waves through the region with intrinsic periods above the Brunt-V?is?l? period. The short period disturbances observed in F region bottomside are not evident in TEC. The results demonstrate the capability of PDI to detect ionospheric disturbances with temporal scales down to a few minutes in routine ionogram mode. Future prospects of PDI are outlined.
关键词： ionospheric disturbances,F region,portable digital ionosonde,Doppler-ionograms,TEC
更新于2025-09-10 09:29:36