Searching for Millisecond Pulsars: Surveys, Techniques and Prospects

Searches for millisecond pulsars (which we here loosely define as those with periods $<$ 20 ms) in the Galactic field have undergone a renaissance in the past five years. New or recently refurbished radio telescopes utilizing cooled receivers and state-of-the art digital data acquisition systems are carrying out surveys of the entire sky at a variety of radio frequencies. Targeted searches for millisecond pulsars in point sources identified by the {\it Fermi} Gamma-ray Space Telescope have proved phenomenally successful, with over 50 discoveries in the past five years. The current sample of millisecond pulsars now numbers almost 200 and, for the first time in 25 years, now outnumbers their counterparts in Galactic globular clusters. While many of these searches are motivated to find pulsars which form part of pulsar timing arrays, a wide variety of interesting systems are now being found. Following a brief overview of the millisecond pulsar phenomenon, we describe these searches and present some of the highlights of the new discoveries in the past decade. We conclude with predictions and prospects for ongoing and future surveys.Comment: 16 pages, 3 figures, accepted for publication in Classical and Quantum gravit

Space Generic Open Avionics Architecture (SGOAA) reference model technical guide

This report presents a full description of the Space Generic Open Avionics Architecture (SGOAA). The SGOAA consists of a generic system architecture for the entities in spacecraft avionics, a generic processing architecture, and a six class model of interfaces in a hardware/software system. The purpose of the SGOAA is to provide an umbrella set of requirements for applying the generic architecture interface model to the design of specific avionics hardware/software systems. The SGOAA defines a generic set of system interface points to facilitate identification of critical interfaces and establishes the requirements for applying appropriate low level detailed implementation standards to those interface points. The generic core avionics system and processing architecture models provided herein are robustly tailorable to specific system applications and provide a platform upon which the interface model is to be applied

Space Station Freedom (SSF) Data Management System (DMS) performance model data base

The purpose of this document was originally to be a working document summarizing Space Station Freedom (SSF) Data Management System (DMS) hardware and software design, configuration, performance and estimated loading data from a myriad of source documents such that the parameters provided could be used to build a dynamic performance model of the DMS. The document is published at this time as a close-out of the DMS performance modeling effort resulting from the Clinton Administration mandated Space Station Redesign. The DMS as documented in this report is no longer a part of the redesigned Space Station. The performance modeling effort was a joint undertaking between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Flight Data Systems Division (FDSD) and the NASA Ames Research Center (ARC) Spacecraft Data Systems Research Branch. The scope of this document is limited to the DMS core network through the Man Tended Configuration (MTC) as it existed prior to the 1993 Clinton Administration mandated Space Station Redesign. Data is provided for the Standard Data Processors (SDP's), Multiplexer/Demultiplexers (MDM's) and Mass Storage Units (MSU's). Planned future releases would have added the additional hardware and software descriptions needed to describe the complete DMS. Performance and loading data through the Permanent Manned Configuration (PMC) was to have been included as it became available. No future releases of this document are presently planned pending completion of the present Space Station Redesign activities and task reassessment

RF Breakdown in Drift Tube Linacs

The highest RF electric field in drift-tube linacs (DTLs) often occurs on the face of the first drift tube. Typically this drift tube contains a quadrupole focusing magnet whose fringing fields penetrate the face of the drift tube parallel to the RF electric fields in the accelerating gap. It has been shown that the threshold for RF breakdown in RF cavities may be reduced in the presence of a static magnetic field. This note offers a “rule of thumb” for picking the maximum “safe” surface electric field in DTLs based on these measurements

A New Site Index Model for Intensively Managed Loblolly Pine (Pinus taeda) Plantations in the West Gulf Coastal Plain

Site index (SI) estimation for loblolly pine (Pinus taeda L.) plantations is important for the successful management of this important commercial tree species in the West Gulf Coastal Plain of the United States. This study evaluated various SI models for intensively managed loblolly plantations in the West Gulf Coastal Plain using data collected from permanent plots installed in intensively managed loblolly pine plantations across east Texas and western Louisiana. Six commonly used SI models (Cieszewski GADA model, both Chapman-Richards ADA and GADA models, both Schumacher ADA and GADA models, and McDill-Amateis GADA model) were fit to the data and compared. The Chapman-Richards GADA model and the McDill-Amateis GADA model were similar and best in their fit statistics. These two models were further compared to the existing models (Diéguez-Aranda et al. 2006 (DA2006), Coble and Lee 2010 (CL2010)) commonly used in the region. Both the Chapman-Richards GADA and the McDill-Amateis GADA models consistently predicted greater heights up to age 25 than the models of DA2006 and CL2010, with larger height differences for the higher quality sites, but predicted shorter heights thereafter. Ultimately, the McDill-Amateis GADA model was chosen as the best model for its consistency in predicting reasonable heights extrapolated beyond the range of the data. Foresters can use this model to make more informed silvicultural prescriptions for intensively managed loblolly pine plantations in the West Gulf Coastal Plain

Short-term carbon partitioning fertilizer responses vary among two full-sib loblolly pine clones

We investigated the effects of fertilizer application on the partitioning of gross primary productivity (GPP) between contrasting full-sib clones of Pinus taeda (L.). Our objective was to determine if fertilizer growth responses resulted from similar short-term changes to partitioning. A modeling approach incorporating respiratory carbon (C) fluxes, soil CO2 efflux (FS), and biomass was applied to a factorial design with two clones, fertilizer and control treatments, and four sequential monthly harvests of seedlings planted in a greenhouse. Partitioning was integrated over 121 days to above, belowground, and total net primary production (ANPP + BNPP = NPP), total belowground C flux (TBCF), aboveground plant respiration (APR), and FS. While both clones showed similar GPP and responses to fertilizer application, they did so by partitioning GPP in different ways. Fertilizer application increased GPP and resulted in corresponding increases in ANPP, BNPP, and TBCF (p \u3c 0.01). When considered as a fraction of GPP partitioned, differences between clones emerged. Clone-by-fertilizer interactions for carbon use efficiency (i.e. NPP / GPP), ANPP / GPP, and APR / GPP were all observed (p \u3c 0.10). TBCF was significantly greater in one clone, indicating that plant-soil interactions could be affected by clonespecific partitioning. The other clone had greater growth efficiency (ANPP / GPP) without fertilizer, but with fertilizer application the clones were similar. Our results suggest multiple possible short-term ecophysiological mechanisms are responsible for fertilizer growth response in different yet closely related clones

Implementing the space shuttle data processing system with the space generic open avionics architecture

This paper presents an overview of the application of the Space Generic Open Avionics Architecture (SGOAA) to the Space Shuttle Data Processing System (DPS) architecture design. This application has been performed to validate the SGOAA, and its potential use in flight critical systems. The paper summarizes key elements of the Space Shuttle avionics architecture, data processing system requirements and software architecture as currently implemented. It then summarizes the SGOAA architecture and describes a tailoring of the SGOAA to the Space Shuttle. The SGOAA consists of a generic system architecture for the entities in spacecraft avionics, a generic processing external and internal hardware architecture, a six class model of interfaces and functional subsystem architectures for data services and operations control capabilities. It has been proposed as an avionics architecture standard with the National Aeronautics and Space Administration (NASA), through its Strategic Avionics Technology Working Group, and is being considered by the Society of Aeronautic Engineers (SAE) as an SAE Avionics Standard. This architecture was developed for the Flight Data Systems Division of JSC by the Lockheed Engineering and Sciences Company, Houston, Texas

Receipt, 28 September 1843

https://egrove.olemiss.edu/aldrichcorr_b/1063/thumbnail.jp

An avionics scenario and command model description for Space Generic Open Avionics Architecture (SGOAA)

This paper presents a description of a model for a space vehicle operational scenario and the commands for avionics. This model will be used in developing a dynamic architecture simulation model using the Statemate CASE tool for validation of the Space Generic Open Avionics Architecture (SGOAA). The SGOAA has been proposed as an avionics architecture standard to NASA through its Strategic Avionics Technology Working Group (SATWG) and has been accepted by the Society of Automotive Engineers (SAE) for conversion into an SAE Avionics Standard. This architecture was developed for the Flight Data Systems Division (FDSD) of the NASA Johnson Space Center (JSC) by the Lockheed Engineering and Sciences Company (LESC), Houston, Texas. This SGOAA includes a generic system architecture for the entities in spacecraft avionics, a generic processing external and internal hardware architecture, and a nine class model of interfaces. The SGOAA is both scalable and recursive and can be applied to any hierarchical level of hardware/software processing systems

Space Generic Open Avionics Architecture (SGOAA) standard specification

The purpose of this standard is to provide an umbrella set of requirements for applying the generic architecture interface model to the design of a specific avionics hardware/software system. This standard defines a generic set of system interface points to facilitate identification of critical interfaces and establishes the requirements for applying appropriate low level detailed implementation standards to those interface points. The generic core avionics system and processing architecture models provided herein are robustly tailorable to specific system applications and provide a platform upon which the interface model is to be applied