Complete mitochondrial genome of Cyclopelta obscura (Lepeletier & Serville, 1825) (Hemiptera: Pentatomoidea: Dinidoridae) and phylogenetic analysis of Pentatomoidea species.

Cyclopelta obscura is a crop pest, which mainly damages legumes, especially Robinia pseudoacacia and Cercis chinensis. In recent years, many mitochondrial and nuclear DNA sequences of C. obscura have been sequenced and used for phylogenetic inference. However, the complete mitogenome has not been reported yet and studies on the phylogenetic relationships within Dinidoridae are rare. In this study, we sequenced the mitogenome of C. obscura and conducted comparative mitogenomic analyses of seven Dinidoridae species based on several different factors. The length of the mitogenome is 15,426 bp, which includes 37 typical mitochondrial genes (13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs) and a control region (796 bp long), as well as 13 intergenic spacers and 8 overlapping regions. Most PCGs of C. obscura began with the classical start codon ATN, while cox1 and nad4l used TTG, and nad1 used GTG. The Dinidoridae mitogenomes are highly conserved in terms of nucleotide composition, the codon usage of PCGs, and the secondary structure of tRNA. Phylogenetic analysis based on four datasets with two methods recovered the Dinidoridae as a monophyletic group with strong support values. All results indicate that Dinidoridae formed a sister group to Tessaratomidae, and (Tessaratomidae + Dinidoridae) formed a sister group to Cydnidae in most of the phylogenetic trees. Additionally, seven species within the Dinidoridae, we observed the following relationship: (Eumenotes sp. + (Cyclopelta parva + C. obscura)) + ((Megymenum gracilicorne + Megymenum brevicorne) + (Coridius chinensis + Coridius brunneu)).

Research on the eLoran Differential Timing Method.

An enhanced long-range navigation (eLoran) system was selected as the backup of Global Navigation Satellite Systems (GNSS), and experts and scholars are committed to improving the accuracy of the eLoran system such that its accuracy is close to the GNSS system. A differential method called eLoran differential timing technology is applied to the eLoran system, which has been used in maritime applications of eLoran. In this study, an application of eLoran differential timing technology in a terrestrial medium is carried out. Based on the eLoran timing service error, the correlation of the timing service error is analyzed in theory quantitatively to obtain the range of the difference station in the ground. The results show that to satisfy the timing accuracy of 100 ns, the action range of eLoran difference station on the land needs to be less than 55 km. Therefore, the eLoran differential method is proposed, and in the difference station, the theoretical calculation is combined with the measurement of the signal delay to obtain the difference information, which is sent to the users to adjust the prediction delay and improve the eLoran timing precision. The experiment was carried out in the Guan Zhong Plain, and the timing error of the user decreased from 394.7287 ns (pre-difference) to 19.5890 ns (post-difference). The proposed method is found to effectively enhance the timing precision of the eLoran system within the scope of action.

High-Accuracy Positioning Based on Pseudo-Ranges: Integrated Difference and Performance Analysis of the Loran System.

The Long Range Navigation (Loran) system as a backup of the Global Navigation Satellite System (GNSS) is a good choice. The dominant deterioration factors of position accuracy are the pseudo-range measurement errors and the geometric dilution of precision (GDOP). This paper focuses on the algorithm integrated difference with pseudo-ranges to improve the position accuracy. Firstly, the theoretical prediction of propagation delay and raw measurement are compared. The results show that the measured pseudo-range consists of a constant term and a temporal term, which reflect the propagation situation along the true path. Secondly, a position solution algorithm based on a pseudo-range and difference is presented, exceeding the limit of a single chain. Finally, some simulation tests are implemented utilizing the new proposed position algorithm to verify the differential performance. This method can reduce the GDOP conveniently through increasing the number of transmitters. In view of the amplitude and characteristics of errors in measurement, systematic error and random noise are distinguished and discussed. The absolute accuracy responds to the pseudo-range bias that is different from geometric distance and repeatable accuracy is mainly influenced by random noise. The difference method can improve the absolute accuracy via the correction degree without changing the geometry of the transmitters.

Simultaneous normal and parallel incidence planar left-handed metamaterial.

We investigate numerically the negative refraction of a simultaneous normal and parallel incidence planar left-handed metamaterial (LHM) in this paper. This LHM is comprised of fourfold C-shaped rings, which are printed on both sides of the substrates symmetrically, and it can exhibit left-handed properties with electromagnetic wave incident in three different directions. The retrieved result and the simulated result verify the left-handed properties of the fourfold C-shaped metamaterial very well. Then the different electric responses of the normal and parallel incidence cases to the incident electromagnetic wave are discussed, and it is due to the different distribution of the induced currents in the metallic wires.

Numerical studies of a low-loss and broad-pass-band single-sided-structure left-handed metamaterial.

A single-sided structure left-handed metamaterial (LHM), of which the symmetric paired split-ring resonators are connected directly through cut wires, is discussed in this paper. This connected single-sided LHM can exhibit a low loss and broad negative refraction passband. Good agreement of the retrieved result and the simulated result verify the above conclusion by comparison with the in-plane case and the off-plane case [T. Koschny, M. Kafesaki, E. N. Economou, and C. M. Soukoulis, Phys. Rev. Lett. 93, 107402 (2004)].