Recent Magnetized Liner Inertial Fusion experiments at the Sandia National Laboratories Z pulsed power facility have featured a PDV (Photonic Doppler Velocimetry) diagnostic in the final power feed section for measuring load current. In this paper, we report on an anomalous pressure that is detected on this PDV diagnostic very early in time during the current ramp. Early time load currents that are greater than both B-dot upstream current measurements and existing Z machine circuit models by at least 1 MA would be necessary to describe the measured early time velocity of the PDV flyer. This leads us to infer that the pressure producing the early time PDV flyer motion cannot be attributed to the magnetic pressure of the load current but rather to an anomalous pressure. Using the MHD code ALEGRA, we are able to compute a time-dependent anomalous pressure function, which when added to the magnetic pressure of the load current, yields simulated flyer velocities that are in excellent agreement with the PDV measurement. We also provide plausible explanations for what could be the origin of the anomalous pressure.
Distributed Energy Resources (DER) are being added to the nation's electric grid, and as penetration of these resources increases, they have the potential to displace or offset large-scale, capital-intensive, centralized generation. Integration of DER into operation of the traditional electric grid requires automated operational control and communication of DER elements, from system measurement to control hardware and software, in conjunction with a utility's existing automated and human-directed control of other portions of the system. Implementation of DER technologies suggests a number of gaps from both a security and a policy perspective.
We report a simple method to synthesize V 4+ (VO 2+ ) electrolytes as feedstock for all- vanadium redox flow batteries (RFB). By dissolving V 2 O 5 in aqueous HCl and H 2 SO 4 , subsequently adding glycerol as a reducing agent, we have demonstrated an inexpensive route for electrolyte synthesis to concentrations >2.5 M V 4+ (VO 2+ ). Electrochemical analysis and testing of laboratory scale RFB demonstrate improved thermal stability across a wider temperature range (-10-65 degC) for V 4+ (VO 2+ ) electrolytes in HCl compared to in H 2 SO 4 electrolytes.
The thermal degradation of two polyurethane elastomers was investigated via thermal gravimetric analysis coupled with gas chromatography/ma ss spectrometry. Decomposition occur s in a multi - step fashion with similar onset temperatures for both materials. Apparent activation energy plots were calculated inside Model - Free Kinetics software and utilized to construct conversion and isothermal conversion tables . These tables predicted material degradation as a function of temperature and time. Isothermal experiments were performed and found to be in good agreement with the predictions made from the Model - Free Kinetic s software package. Volatile products evolved during the multistep decomposition were captured at various times and analyzed using the coupled gas chromatography/mass spectrometry system . This analysis demonstrated strong correlation between the degradation products and known decomposition mechanisms for polyurethanes.
Since our last paper, cyber attacks have shown no evidence of declining in frequency or sophistication. We claim that applying isolation zones is an effective way to defend cyber systems; our team proposes a simulation and mathematical model that provide numerical data that supports this claim. This paper extends our earlier cyber zone defense (CZD) framework in two critical ways. First, we relax our assumption that zones completely isolate nodes and consider interzone boundaries to be porous. Second, we investigate methods to estimate one of the legacy parameters inherited from our earlier work and the new porosity parameter. The extended simulation and model more closely approximate real world cyber systems and have lower residuals than our previous investigation.
Silicon-based metal-oxide-semiconductor quantum dots are prominent candidates for high-fidelity, manufacturable qubits. Due to silicon's band structure, additional low-energy states persist in these devices, presenting both challenges and opportunities. Although the physics governing these valley states has been the subject of intense study, quantitative agreement between experiment and theory remains elusive. Here, we present data from an experiment probing the valley states of quantum dot devices and develop a theory that is in quantitative agreement with both this and a recently reported experiment. Through sampling millions of realistic cases of interface roughness, our method provides evidence that the valley physics between the two samples is essentially the same.
The Sandia Data Archive (SDA) format is special implementation the HDF5 (Hierarchal Data Format, version 5) standard. Archive files store data in records identified with a unique text label. Primitive records store numeric, logical, and character arrays of arbitrary size and dimensionality. Compound records store composite MAT- LAB variables--cell arrays, structures, and objects--with arbitrary nesting. External records allow text/binary files to be stored alongside archived data or division of a large file into smaller archives for transmission. This report documents version 1.1 of the SDA standard, which adds support for structure and object arrays. The basic principles of SDA remain unchanged from version 1.0, with minor enhancements and bug fixes. The Sandia Mat lab AnalysiS Hierarchy (SMASH) toolbox uses SDA extensively; support utilities from the toolbox are highlighted here. Although the SDA format is designed around MATLAB, its use of HDF5 allows adoption in other computer languages.
