Colorado Northwestern Community College

Railway reference stations are characterized by long span, strip distribution, cross-regional service, weak graphical structure, and requiring high monitoring precision. In view of this, the traditional modeling approaches for reference uniformity have become no longer quite applicable. Currently, coordinates reference maintenance is conducted separately in each area, so that there exist differences among various reference stations in respect of data processing software, mathematical physical model, solution strategy, adjustment method, and revision cycle. This causes systematic deviation in satellite navigation and positioning service reference between different areas. To ensure the uniformity and timeliness of high-precision location-based service reference of national railways, this study is intended to simulate cross-region, strip, isoheight-shape and Y-shape layout modes based on the actual situation of railway observation network, and implement selection of reference station control points, networking solution scheme design and result analysis considering the reference uniformity solution requirements of different layout modes to propose an inclusive coordinates reference uniformity solution scheme applicable for various strip layout modes and provide a practicable reference for the coordinates reference uniformity solution of reference stations of railways and shipping lanes. This is significant to the coordinates uniformity and regular updating maintenance of high-precision service datum network of railways.

We used solid-phase microextraction of headspace samples followed by gas chromatography and mass spectrometry to identify and quantify the major volatile compounds produced by the buds and corollas of Ipomopsis aggregata (Polemoniaceae), and we compared them to a sympatric, confamilial plant species, Polemonium foliosissimum. The two species have distinct floral morphologies and pollinators, but share a common predispersal seed predator that oviposits under the calyces of buds. Ipomopsis aggregata buds emitted fewer compounds than the corollas. The buds of I. aggregata were dominated by alpha-pinene and, to a lesser extent, beta-pinene. The corollas of I. aggregata emitted a mixture of 10 compounds. Like the buds, I. aggregata corollas produced relatively high concentrations of alpha-pinene as well as caryophyllene. In addition, the emission of four terpenoids, three esters, and one ketone added to the volatile bouquet of the corollas. Polemonium foliosissimum buds also emitted fewer compounds than the corollas. The buds of P. foliosissimum were dominated by beta-pinene and, to a lesser extent, alpha-pinene. The corollas of P. foliosissimum were also dominated by beta-pinene along with three terpenoids, three alcohols, one ester, and two aldehydes. Comparing I. aggregata and P. foliosissimum, bud samples from both species produced considerable amounts of alpha- and beta-pinene. Ipomopsis aggregata emitted more alpha-pinene than beta-pinene, while P. foliosissimum emitted more beta-pinene. The corollas of the two species, however, differed in their volatile bouquet. The partition of volatiles between I. aggregata and P. foliosissimum buds and corollas and differences in volatile production between I. aggregata and P. foliosissimum are consistent with selection pressures exerted by organisms interacting with these plants.