Blunting the Spike: the CV Minimum Period

The standard picture of CV secular evolution predicts a spike in the CV distribution near the observed short-period cutoff P_0 ~ 78 min, which is not observed. We show that an intrinsic spread in minimum (`bounce') periods P_b resulting from a genuine difference in some parameter controlling the evolution can remove the spike without smearing the sharpness of the cutoff. The most probable second parameter is different admixtures of magnetic stellar wind braking (at up to 5 times the GR rate) in a small tail of systems, perhaps implying that the donor magnetic field strength at formation is a second parameter specifying CV evolution. We suggest that magnetic braking resumes below the gap with a wide range, being well below the GR rate in most CVs, but significantly above it in a small tail.Comment: 5 pages, 4 figures; accepted for publication in MNRA

A New Evolutionary Picture for CVs and LMXBs

We consider an alternative to the standard picture of CV and LMXB evolution, namely the idea that most CVs (and by extension LMXBs) may not yet have had time to evolve to their theoretical minimum orbital periods. We call this the Binary Age Postulate (BAP). The observed short-period cutoff in the CV histogram emerges naturally as the shortest period yet reached in the age of the Galaxy, while the post-minimum-period space density problem is removed. The idea has similar desirable consequences for LMXBs. In both cases systems with nuclear-evolved secondary stars form a prominent part of the short-period distributions. Properties such as the existence and nature of ultrashort-period systems, and the spread in mass transfer rates at a given orbital period, are naturally reproduced.Comment: 10 pages, 6 figures; to appear in 'The Physics of Cataclysmic Variables and Related Objects', Goettingen, August 5-10, 200

A New Evolutionary Picture for CVs and LMXBs II. The Impact of Thermal-Timescale Mass Transfer

Depending on the outcome of pre-CV formation, mass transfer may set in under thermally unstable conditions in a significant number of systems. Full computations have shown that such an early phase of thermal-timescale mass transfer usually leads to ordinary looking CVs, but these do also show some unusual properties (e.g. chemical anomalies in later stages). Rather than investigating the common envelope evolution leading to pre-CVs, we study the properties of multiple evolutionary tracks starting with a phase of thermal-timescale mass transfer. Apart from fitting unusual CVs (like AE Aqr), global properties of the CV population as a whole give indications that this is indeed the channel where many CVs come from.Comment: 10 pages, 4 figures; to appear in 'The Physics of Cataclysmic Variables and Related Objects', Goettingen, August 5-10, 200

Wave shapes in alternating DSC

ADSC with its periodical temperature programs combines the features of DSC measured at high heating rate (high sensitivity) with those at low heating rate (high temperature resolution). In addition, the "reversing” cp effects can be separated from the "non-reversing” latent heat effects. Various periodical temperature programs can be applied. This paper compares the different possible temperature programs and their algorithms for the cp determination for metal, metal oxide and polymer of various properties. Simulated and measured results for various wave shapes and samples are presented. The relevant sample properties and their influence on the measurements are identified and guiding rules for the proper choice of the various experimental parameters are given. Measurements with different samples, performed with the new METTLER TOLEDO STARe-System, are shown and compared with the simulation results. The simulations and the measurements clearly show that the alternating techniques can yield new information about sample properties, but are susceptible to the proper choice of the various experimental parameter

Exploring Blockchain Adoption Supply Chains: Opportunities and Challenges

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumThe 2018 release of the DoD’s Digital Engineering (DE) strategy and the success of applying DE methods in the mechanical and electrical engineering domains motivate application of DE methods in other product development workflows, such as systems and/or software engineer-ing. The expected benefits of this are improved communication and traceability with reduced rework and risk. Organizations have demonstrated advantages of DE methods many times over by using model-based design and analysis methods, such as Finite Element Analysis (FEA) or SPICE (Simulation Program with Integrated Circuit Emphasis), to conduct detailed evaluations earlier in the process (i.e., shifting left). However, other domains such as embedded computing resources for cyber physical systems (CPS) have not yet effectively demonstrated how to in-corporate relevant DE methods into their development workflows. Although there is broad sup-port for SysML and there has been significant advancement in specific tools, e.g., MathWorks®, ANSYS®, and Dassault tool offerings, and standards like Modelica and AADL, the DE benefits to CPS engineering have not been broadly realized. In this paper, we will explore why CPS devel-opers have been slow to embrace DE, how DE methods should be tailored to achieve their stakeholders’ goals, and how to measure the effectiveness of DE-enabled workflows.Approved for public release; distribution is unlimited

Digital Engineering Effectiveness

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumThe 2018 release of the DoD’s Digital Engineering (DE) strategy and the success of applying DE methods in the mechanical and electrical engineering domains motivate application of DE methods in other product development workflows, such as systems and/or software engineer-ing. The expected benefits of this are improved communication and traceability with reduced rework and risk. Organizations have demonstrated advantages of DE methods many times over by using model-based design and analysis methods, such as Finite Element Analysis (FEA) or SPICE (Simulation Program with Integrated Circuit Emphasis), to conduct detailed evaluations earlier in the process (i.e., shifting left). However, other domains such as embedded computing resources for cyber physical systems (CPS) have not yet effectively demonstrated how to in-corporate relevant DE methods into their development workflows. Although there is broad sup-port for SysML and there has been significant advancement in specific tools, e.g., MathWorks®, ANSYS®, and Dassault tool offerings, and standards like Modelica and AADL, the DE benefits to CPS engineering have not been broadly realized. In this paper, we will explore why CPS devel-opers have been slow to embrace DE, how DE methods should be tailored to achieve their stakeholders’ goals, and how to measure the effectiveness of DE-enabled workflows.Approved for public release; distribution is unlimited