18,010 research outputs found
Feasibility study on lengthening the high-voltage cable section and reducing the number of cable joints via alternative bonding methods
The mesosphere is perhaps the least explored region in the atmosphere with very few methods of observing. This thesis will primarily be exploring a new technique for measuring the distribution of kinetic energy in the mesosphere across a wide range of spatial and temporal scales. The method being used relies on correlation functions between pairs of meteor measurements. These measurements are made using a network of specular meteor radars located in Northern Norway. This network produced 32 million meteor measurements over a 2 year period. The correlation function estimation method has been previously used on a smaller data set, but has so far not been used for a longer data set and at high latitudes. The main advantage of the new technique is that by studying the second order statistics of the wind field, we can obtain significantly better temporal and spatial resolution than before. Such a large data set allows for great resolution for both spatial and temporal correlation functions. By using temporal correlation functions and the kinetic energy spectrum, different atmospheric wave phenomena can be studied. These include diurnal and semi diurnal tides. The horizontal and vertical correlation functions will be used to verify that the kinetic energy follows a power law, as theoretically expected by the Kolmogorov theory for turbulence. This was done by using a second order structure function applied to correlation functions. The temporal and horizontal correlation functions were used to study the summer-winter variation in kinetic energy, some variation in the temporal domain is the impact from large scale waves as well as in the power spectra were there is a steeper power law slope during the winter. As for the horizontal domain there are differences in kinetic energy in the zonal and meridional direction for both large and small scale waves. The dataset in this thesis a lot more can be found out about the mesosphere, in this thesis only a few of the possibilities are explored. The results are in agreement with earlier work, confirming the results obtained by the earlier study
SVMTriP: A Method to Predict Antigenic Epitopes Using Support Vector Machine to Integrate Tri-Peptide Similarity and Propensity
Identifying protein surface regions preferentially recognizable by antibodies (antigenic epitopes) is at the heart of new immuno-diagnostic reagent discovery and vaccine design, and computational methods for antigenic epitope prediction provide crucial means to serve this purpose. Many linear B-cell epitope prediction methods were developed, such as BepiPred, ABCPred, AAP, BCPred, BayesB, BEOracle/BROracle, and BEST, towards this goal. However, effective immunological research demands more robust performance of the prediction method than what the current algorithms could provide. In this work, a new method to predict linear antigenic epitopes is developed; Support Vector Machine has been utilized by combining the Tri-peptide similarity and Propensity scores (SVMTriP). Applied to non-redundant B-cell linear epitopes extracted from IEDB, SVMTriP achieves a sensitivity of 80.1% and a precision of 55.2% with a five-fold cross-validation. The AUC value is 0.702. The combination of similarity and propensity of tri-peptide subsequences can improve the prediction performance for linear B-cell epitopes. Moreover, SVMTriP is capable of recognizing viral peptides from a human protein sequence background. A web server based on our method is constructed for public use. The server and all datasets used in the current study are available at http://sysbio.unl.edu/SVMTriP
Birth places of extreme ultraviolet waves driven by impingement of solar jets upon coronal loops
Solar extreme ultraviolet (EUV) waves are large-scale propagating
disturbances in the corona. It is generally believed that the vital key for the
formation of EUV waves is the rapid expansion of the loops that overlie
erupting cores in solar eruptions, such as coronal mass ejections (CMEs) and
solar jets. However, the details of the interaction between the erupting cores
and overlying loops are not clear, because that the overlying loops are always
instantly opened after the energetic eruptions. Here, we present three typical
jet-driven EUV waves without CME to study the interaction between the jets and
the overlying loops that remained closed during the events. All three jets
emanated from magnetic flux cancelation sites in source regions. Interestingly,
after the interactions between jets and overlying loops, three EUV waves
respectively formed ahead of the top, the near end (close to the jet source),
and the far (another) end of the overlying loops. According to the magnetic
field distribution of the loops extrapolated from Potential Field Source
Surface method, it is confirmed that the birth places of three jet-driven EUV
waves were around the weakest magnetic field strength part of the overlying
loops. We suggest that the jet-driven EUV waves preferentially occur at the
weakest part of the overlying loops, and the location can be subject to the
magnetic field intensity around the ends of the loops
- …