76 research outputs found
New Air-Launched Small Missile (ALSM) Flight Testbed for Hypersonic Systems
A new testbed for hypersonic flight research is proposed. Known as the Phoenix air-launched small missile (ALSM) flight testbed, it was conceived to help address the lack of quick-turnaround and cost-effective hypersonic flight research capabilities. The Phoenix ALSM testbed results from utilization of two unique and very capable flight assets: the United States Navy Phoenix AIM-54 long-range, guided air-to-air missile and the NASA Dryden F-15B testbed airplane. The U.S. Navy retirement of the Phoenix AIM-54 missiles from fleet operation has presented an excellent opportunity for converting this valuable flight asset into a new flight testbed. This cost-effective new platform will fill an existing gap in the test and evaluation of current and future hypersonic systems for flight Mach numbers ranging from 3 to 5. Preliminary studies indicate that the Phoenix missile is a highly capable platform. When launched from a high-performance airplane, the guided Phoenix missile can boost research payloads to low hypersonic Mach numbers, enabling flight research in the supersonic-to-hypersonic transitional flight envelope. Experience gained from developing and operating the Phoenix ALSM testbed will be valuable for the development and operation of future higher-performance ALSM flight testbeds as well as responsive microsatellite small-payload air-launched space boosters
Empirical regularities of order placement in the Chinese stock market
Using ultra-high-frequency data extracted from the order flows of 23 stocks
traded on the Shenzhen Stock Exchange, we study the empirical regularities of
order placement in the opening call auction, cool period and continuous
auction. The distributions of relative logarithmic prices against reference
prices in the three time periods are qualitatively the same with quantitative
discrepancies. The order placement behavior is asymmetric between buyers and
sellers and between the inside-the-book orders and outside-the-book orders. In
addition, the conditional distributions of relative prices in the continuous
auction are independent of the bid-ask spread and volatility. These findings
are crucial to build an empirical behavioral microscopic model based on order
flows for Chinese stocks.Comment: 15 Elsart page including 1 table and 5 figure
JPL Space Telecommunications Radio System Operating Environment
A flight-qualified implementation of a Software Defined Radio (SDR) Operating Environment for the JPL-SDR built for the CoNNeCT Project has been developed. It is compliant with the NASA Space Telecommunications Radio System (STRS) Architecture Standard, and provides the software infrastructure for STRS compliant waveform applications. This software provides a standards-compliant abstracted view of the JPL-SDR hardware platform. It uses industry standard POSIX interfaces for most functions, as well as exposing the STRS API (Application Programming In terface) required by the standard. This software includes a standardized interface for IP components instantiated within a Xilinx FPGA (Field Programmable Gate Array). The software provides a standardized abstracted interface to platform resources such as data converters, file system, etc., which can be used by STRS standards conformant waveform applications. It provides a generic SDR operating environment with a much smaller resource footprint than similar products such as SCA (Software Communications Architecture) compliant implementations, or the DoD Joint Tactical Radio Systems (JTRS)
Dynamics of Bid-ask Spread Return and Volatility of the Chinese Stock Market
Bid-ask spread is taken as an important measure of the financial market
liquidity. In this article, we study the dynamics of the spread return and the
spread volatility of four liquid stocks in the Chinese stock market, including
the memory effect and the multifractal nature. By investigating the
autocorrelation function and the Detrended Fluctuation Analysis (DFA), we find
that the spread return is lack of long-range memory, while the spread
volatility is long-range time correlated. Moreover, by applying the
Multifractal Detrended Fluctuation Analysis (MF-DFA), the spread return is
observed to possess a strong multifractality, which is similar to the dynamics
of a variety of financial quantities. Differently from the spread return, the
spread volatility exhibits a weak multifractal nature
How markets slowly digest changes in supply and demand
In this article we revisit the classic problem of tatonnement in price
formation from a microstructure point of view, reviewing a recent body of
theoretical and empirical work explaining how fluctuations in supply and demand
are slowly incorporated into prices. Because revealed market liquidity is
extremely low, large orders to buy or sell can only be traded incrementally,
over periods of time as long as months. As a result order flow is a highly
persistent long-memory process. Maintaining compatibility with market
efficiency has profound consequences on price formation, on the dynamics of
liquidity, and on the nature of impact. We review a body of theory that makes
detailed quantitative predictions about the volume and time dependence of
market impact, the bid-ask spread, order book dynamics, and volatility.
Comparisons to data yield some encouraging successes. This framework suggests a
novel interpretation of financial information, in which agents are at best only
weakly informed and all have a similar and extremely noisy impact on prices.
Most of the processed information appears to come from supply and demand
itself, rather than from external news. The ideas reviewed here are relevant to
market microstructure regulation, agent-based models, cost-optimal execution
strategies, and understanding market ecologies.Comment: 111 pages, 24 figure
Detailed Pilots Specification
The Electronic Archiving Service consists of a series of activities covered by software tools and manual workflow steps. These tools are currently partly in existence, some are being developed by E-ARK project, many more are to be added by developments of the digital preservation community in the future. The role of this report is to identify the most relevant scenarios for the E-ARK Service, define which scenario which level of activity is needed in order to bridge the gap of the currently existing solutions (e.g. integration, software development, interface definition
Documentation, Common Information and Short Overview of the E-ARK pilots
This report contains the common information and short overview of the pilots, along with references to the final version of the Pilot Definition Excel files and Pilot Documentation Packages
A large scale hearing loss screen reveals an extensive unexplored genetic landscape for auditory dysfunction
The developmental and physiological complexity of the auditory system is likely reflected in the underlying set of genes involved in auditory function. In humans, over 150 non-syndromic loci have been identified, and there are more than 400 human genetic syndromes with a hearing loss component. Over 100 non-syndromic hearing loss genes have been identified in mouse and human, but we remain ignorant of the full extent of the genetic landscape involved in auditory dysfunction. As part of the International Mouse Phenotyping Consortium, we undertook a hearing loss screen in a cohort of 3006 mouse knockout strains. In total, we identify 67 candidate hearing loss genes. We detect known hearing loss genes, but the vast majority, 52, of the candidate genes were novel. Our analysis reveals a large and unexplored genetic landscape involved with auditory function
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