Debye formulas are widely used to describe the electrical dispersion characteristics of a uniform lossy material. Debye model uses some empirical coefficients to control the shape and position of spectroscopy curves. It can fit most of the data from experiments. A two-layered model is investigated through its equivalent Debye circuit model. A Finite Difference Method (FDM) is developed to extract the effective permittivity and conductivity of a two-layered model as the verification of the analytical derivation. The computation results indicate the results obtained from FDM and the layered Debye formulas agree very well, which shows the validity of the layered Debye formulas in terms of the original circuit parameters. The derived formulas are used to analyze the relationship between the effective electrical spectra and the electrical parameters of each layer. A few examples are given in the discussions. And it can be concluded that: (1) with the increase of the average value of the conductivity of the two layers, the spectra of effective permittivity transition area shifts to higher frequencies; while the spectra of effective conductivity transition kept the same with the values decrease; (2) with the increase of the average value of the relative permittivity of the two layers, the transition area of the spectra of effective permittivity kept the same with values increase; and the transition area of the spectra of effective conductivity shifts to the lower frequencies; (3) the effective permittivity enhances at the lower frequency region as the ratio between the conductivity of two layers increase.

Program inversion has been successfully applied to several areas such as optimistic parallel discrete event simulation (OPDES) and reverse debugging. This paper introduces a new program inversion algorithm for imperative languages, and focuses on handling arbitrary control flows and basic operations. By building a value search graph that represents recoverability relationships between variable values, we turn the problem of recovering previous values into a graph search one. Forward and reverse code is generated according to the search results. We have implemented our algorithm as part of a compiler framework named Backstroke, a C++ source-to-source translator based on ROSE compiler. Backstroke targets optimistic simulation codes and automatically generates a reverse function to recover values modified by a target function. Experimental results show that our method is effective and produces better performance than previously proposed methods.

We introduce Backstroke, a new open source framework for the automatic generation of reverse code for functions written in C++. Backstroke enables reverse computation for optimistic parallel discrete event simulations. It is built over the ROSE open-source compiler infrastructure, and handles complex C++ features including pointers and pointer types, arrays, function and method calls, class types, inheritance, polymorphism, virtual functions, abstract classes, templated classes and containers. Backstroke also introduces new program inversion techniques based on advanced compiler analysis tools built into ROSE. We explore and illustrate some of the complex language and semantic issues that arise in generating correct reverse code for C++ functions. INTRODUCTIONBackstroke is a new open source framework for the automatic generation of reverse code for functions written in C++. It is built on ROSE, a widely used source-to-source compiler infrastructure that has been under development at Lawrence Livermore National Laboratory for a decade (Quinlan 2011). The primary purpose of Backstroke is to enable reverse computation for fast, efficient rollback in optimistic parallel discrete event simulations. Reverse computation is a well established technique now, but major practical barriers still prevent its widespread adoption. It is difficult to create correct and efficient reverse methods by hand, and unrealistic to require programmers to do so. Further, since the number of times an event is rolled back is unpredictable, simple bugs in reverse code frequently act as nondeterministic "Heisenbugs", making debugging very difficult. These considerations suggest automatic generation of reverse code (Perumalla 1999, Carothers, Perumalla, and. Backstroke takes this approach, but advances it considerably beyond prior systems. In particular, it can reverse more complex language constructs than prior work, since it applies to C++ rather than just C, and it serves as a general framework allowing experimentation with many different inversion techniques. We will describe some of the general approaches to automatic generation of reverse code, and explore language and semantic issues that arise in generating correct reverse code for C++ functions. CONTEXT AND RELATED WORKA parallel discrete event simulation (PDES) program consists of logical processes (LPs) that execute concurrently and exchange timestamped event messages. A synchronization algorithm is required to ensure each LP processes events in non-decreasing timestamp order. Optimistic synchronization uses rollback to undo the computation of events that are performed out of timestamp order (Jefferson 1985). Parallel discrete event simulation and optimistic execution are described in detail in (Fujimoto 2000). Reverse computation is a technique to efficiently implement event rollback (Carothers, Perumalla and Fujimoto, 1999;Tang Perumalla, and Fujimoto 2006, Naborskyy andFujimoto 2007). Each event routine is instrumented to save a minimal amount of control and data informat...

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Almost all existing studies on inter-satellite radio-frequency (RF) measurement have focused on two-satellite formations. Although some frequency division multiple access and code division multiple access multisatellite RF measurement schemes have been proposed, their poor scalability does not satisfy the inter-satellite measurement requirements of multisatellite formations, especially large-scale formations. Two-way ranging (TWR), which is based on a time division mechanism, is an effective solution that has been used for inter-satellite links in the global positioning system and Beidou navigation constellations. However, the high measurement accuracy achieved with TWR in these navigation constellations is heavily reliant on high-performance atomic clocks and the assistance of navigation ephemeris, which are not available on microsatellite platforms. This work focuses on a scalable multisatellite measurement scheme that adopts a distributed broadcast-based time division multiple access mechanism as the media access control layer and uses an asymmetric double-side TWR method as the physical layer. The measurement performance of the proposed scheme is evaluated through in-depth theoretical modeling, simulation verification, and experimental validation, along with a comprehensive comparison with the conventional TWR method. The experimental results show that centimeter-level measurement accuracy can be achieved with the proposed scheme when only a common miniaturized frequency source is used. This accuracy level is two orders of magnitude better than that of the TWR method, and thus satisfies the application requirements of general large-scale microsatellite formations.