4,354 research outputs found
Improving Broadcast Channel Rate Using Hierarchical Modulation
No full textWe investigate the design of a broadcast system where the aim is to maximise the throughput. This task is usually challenging due to the channel variability. Modern satellite communications systems such as DVB-SH and DVB-S2 mainly rely on time sharing strategy to optimize throughput. They consider hierarchical modulation but only for unequal error protection or backward compatibility purposes. We propose in this article to combine time sharing and hierarchical modulation together and show how this scheme can improve the performance in terms of available rate. We present the gain on a simple channel modeling the broadcasting area of a satellite. Our work is applied to the DVB-SH standard, which considers hierarchical modulation as an optional feature
Comparison of plasma generation behaviors between a single crystal semiconductor bridge (single-SCB) and a polysilicon semiconductor bridge (poly-SCB)
No full textA single crystal semiconductor bridge (single-SCB) has been fabricated by a micro-electro-mechanical system (MEMS) technique based on anisotropic wet etching, where an air gap replaces the oxide layer NOD used as a thermal insulating barrier in the conventional polycrystalline semiconductor bridge (poly-SCB). Upon flowing current in the single-SCB and the poly-SCB, the single-SCB exhibits a second peak of plasma generation at 500 ns, whereas that of the poly-SCB is founded at 600 ns. The results of an electrical experiment are analyzed through a finite element analysis and a simple discrete-element modeling of the thermal structure. From these investigations, it is clear that more effective heat conduction related to the plasma discharge behaviors is achieved in the single-SCB with a simpler thermal structure. (C) 2004 Elsevier B.V. All rights reserved
SH 39
No full textPhotograph of flood damage on Winters Creek Bridge on SH 39, east of Chickasha, Ok, Grady County, May 19, 1949
Characteristics of plasma generated by polysilicon semiconductor bridge (SCB)
No full textIn an effort to elucidate the plasma generation mechanism of the semiconductor bridge (SCB), currents were forced to flow through a polysilicon bridge with a resistance of 1 Omega, while the voltage drop was measured to obtain the in situ power dissipation through the bridge. The energy stored in a 25 muF capacitor was used to activate the plasma. The typical behavior of two peaks in the voltage-time curve was observed. It is inferred from the photodiode signal that the second peak in the voltage curve results from the plasma generation of the bridge material. The breakdown voltage of the electrical discharge at high pressure proved that the SCB is an effective plasma generator. The experimental data for the no-fire condition, directly related to the safety of the explosive system, is compared with the analytical results from a theoretical model. (C) 2002 Elsevier Science B.V. All rights reserved.This research was supported in part by the Dual Use Technology Program of Ministry of National Defense
Pratt Pony Truss Bridge, Sheridan Township, Codington County
No full text35 mm slide, iron trusses with a wood floorDrawer info: Clay-Corson; Sheridan Twp T-116N R-52W (SH)Kodachrome Slide RS CD-SH-10 Pratt Pony Truss Bridge (built 1910) Facing SE 31 Aug 86F
Pratt Pony Truss Bridge, Sheridan Township, Codington County
No full text35 mm slide, iron trusses with a wood floorDrawer info: Clay-Corson; Sheridan Twp T-116N R-52W (SH)Kodachrome Slide RS CD-SH-10 Pratt Pony Truss Bridge (1910) Facing N-NE 29 Aug 86F
Pratt Pony Truss Bridge, Sheridan Township, Codington County
No full text35 mm slide, iron trussesDrawer info: Clay-Corson; Sheridan Twp T-116N R-52W (SH)Kodachrome Slide RS CD-SH-10 Pratt Pony Truss Bridge <-- Pin Connections 33 Aug 86F
Wellesly Sh. W. to Mr. James Meredith (2 October 1962)
No full textSigned by Wellesly Sh. W.https://egrove.olemiss.edu/mercorr_pro/1531/thumbnail.jp
Archeological Survey of Three Bridge Replacements along SH 97 LaSalle and McMullen Counties, Texas.
No full textOn March 12, 2015, TxDOT conducted an intensive archeological survey for the proposed to replacement of three bridges along SH 97 in LaSalle and McMullen Counties. The bridges are located north of the town of Fowlerton, Texas. The first bridge crosses the Frio River, the second crosses a tributary of the Mossy Slough both in LaSalle County. The third bridge crosses the Mossy Slough just past the LaSalle County line in McMullen County. The total area of potential effects (APE) for all three bridge replacements is 8.4 acres. No new ROW or easements are proposed for the project. Although the schematic design plans show only fill being added to the existing ground surface of the roadway approaches, depth of impact for the support pilings is estimated at approximately 50 feet.
A 100 percent pedestrian survey was conducted at all three proposed bridge replacement project areas. The pedestrian survey noted significant ground disturbing impacts from prior bridge construction and utility installation. In particular, extensive fill sections are present to elevate the roadway over the broad floodplain of the Frio River Valley across which all three bridges are located.
Subsequent to the pedestrian survey, backhoe trenching was conducted at the Frio River and Mossy Slough Bridges. The Mossy Slough Tributary Bridge was not trenched based on a combination of factors including modern age, short span, and existing impacts. The observations from both the pedestrian survey and subsurface testing revealed no archeological materials or features. Although trenching at the Frio River Bridge terrace showed a relatively intact soil profile (despite the absence of archeological materials and features), trenching at the Mossy Slough did reveal extensive fill even in the spanned terrace within the APE.
A TxDOT archeologist evaluated the potential for the proposed undertaking to affect archeological historic properties (36 CFR 800.16(l)) or State Antiquities Landmarks (13 TAC 26.12) in the APE for the proposed SH 97 bridge replacements. Based on the combined pedestrian survey of the backhoe trenching, no archeological sites or materials were observed in the proposed project areas. In addition, the majority of the APE had been substantively impacted by prior transportation construction and utilities leaving only small areas of intact alluvium to examine. Based on these observed impacts and the results of the survey, any sites in the APE would likely lack sufficient integrity of location, association, and materials to be able to address important questions of prehistory or history (36CFR60.4 and would not be considered eligible for listing to the NRHP (36 CFR 60.4) or for designation as a SAL (13 TAC 26.8) and no further work is warranted for the project areas
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