Ludlum Measurements (United States)

Conflicting goals of self-organizing components in O-RAN open, modularized architectures present a major issue for the management of telecommunications networks. The use of autonomic network control results in individual management applications making real-time reconfigurations to the network without user intervention. A major unresolved challenge presents as each autonomic agent operates with its own specific goals, resulting in potential conflicting actions. Many orchestration techniques have been proposed to avoid deploying components that do not work together harmoniously due to competing goals and effects. However, efficient operation of a telecommunications network involves trade-offs between competing goals. This paper proposes the CAMINO - Contextually Aware Mediation of Intent for Network Orchestration architecture as an extension to the O-RAN Software Management and Orchestration (SMO) function. CAMINO preemptively detects conflicts between the individual reconfiguration actions of competing components. CAMINO implements a novel, contextual, enhanced intent-based architecture utilizing information from non-traditional sources to determine how to resolve the conflict. CAMINO facilitates the operator’s intent for the network through analysis of both telecommunications data sources and external data sources, i.e., weather, traffic, planned events, incident information. CAMINO preemptively detects conflict between the competing actions of autonomic network configuration functions. Reconfiguration actions in the network that are predicted to cause degradation of Key Performance Indicators (KPIs) can be over-ridden using preemptive conflict detection. CAMINO specifically targets predicted network degradations that conflict with the current intent of the network operator, are contra-indicated by telecommunications data sources, or are assessed as being incompatible with current conditions in the operating environment.

Heteroepitaxial boron carbide (BxC) can be grown on Si face 4H-SiC(0001) using a two-step process involving substrate boridation at 1200$^\circ$C under BCl3 + H2 followed by a chemical vapor deposition (CVD) growth step at 1600$^\circ$C by adding C3H8 precursor. However, in-depth investigation of the early growth stages revealed that complex reactions occur before starting the CVD at high temperature. Indeed, after boridation, the 35 nm BxC buffer layer is covered by an amorphous B-containing layer which evolves and reacts during the temperature ramp up between 1200 to 1600$^\circ$C. Despite the formation of new phases (Si, SiB6), which could be explained by significant solid-state diffusion of Si, C and B elements through the thin BxC layer, the CVD epitaxial re-growth upon reaching 1600$^\circ$C does not seems to be affected by these phases. The resulting single crystalline BxC layers display the epitaxial relationships [1010]BxC(0001)||[1010]4H-SiC(0001). The layers exhibit a B4C composition, e.g. the highest possible C content for the BxC solid solution.

The crosstalk between immune cells and the neurovascular unit plays a pivotal role in neural regeneration following central nervous system (CNS) injury. Maintaining brain immune homeostasis is crucial for restoring neurovascular function. In this study, an interactive bridge was developed via an immunomodulatory hydrogel microsphere to link the interaction network between microglia and the neurovascular unit, thereby precisely regulating immune-neurovascular crosstalk and achieving neural function recovery. This immunomodulatory crosstalk microsphere (MP/RIL4) was composed of microglia-targeted RAP12 peptide-modified interleukin-4 (IL-4) nanoparticles and boronic ester-functionalized hydrogel using biotin-avidin reaction and air-microfluidic techniques. We confirmed that the immunomodulatory microspheres reduced the expression of pro-inflammatory factors including IL-1β, iNOS, and CD86, while upregulating levels of anti-inflammatory factors such as IL-10, Arg-1, and CD206 in microglia. In addition, injection of the MP/RIL4 significantly mitigated brain atrophy volume in a mouse model of ischemic stroke, promoted neurobehavioral recovery, and enhanced the crosstalk between immune cells and the neurovascular unit, thus increasing angiogenesis and neurogenesis of stroke mice. In summary, the immunomodulatory microspheres, capable of orchestrating the interaction between immune cells and neurovascular unit, hold considerable therapeutic potential for ischemic stroke and other CNS diseases.

Hexagonal boron nitride (hBN) presents valuable intrinsic properties and attracts considerable attention for the development of novel two-dimensional (2D) materials-based technologies. Even though huge efforts have been made to improve the bottom-up synthesis of integrated and high quality hBN, the devices presenting the best performances are still made using hBN exfoliated from bulk crystals. In this context, we explore the Polymer-Derived Ceramics (PDC) route coupled to a high temperature process that produces millimetric and high quality hBN crystals. By investigating the (micro)structure of several samples, we demonstrate that the crystal growth occurs by segregation from a Li3BN2-BN solution upon cooling and from hBN seeds. In particular, we show that crystallization can occur at a temperature as low as 1400{\textdegree}C. Overall, these results show that hBN crystal growth in the Li3BN2-BN system is compatible with conventional flux methods that may be the most promising platform for continuous seeded hBN crystal growth.

The thermochromic properties (color change with temperature) of n type doped SiC wafers of different polytypes (3C, 4H and 6H) have been investigated up to 500$^\circ$C under air. It was found that 3C-SiC color passes from bright yellow at room temperature to deep orangeat 500$^\circ$C leading to a color contrast ($\Delta$E) as high as 64. The hexagonal polytypes undergo also a color change upon heating but far less pronounced, with $\Delta$E values <20. All these semiconductors undergo band gap shrinkage upon heating which effect largely participated to the observed color change. This effect is very sensitive for 3C polytypesince its bandgap is already in the visible energy range at room temperature. The thermochromicity of 3C-SiC was found to be reversible thanks to its thermal stability and its resistance towards oxidation.

The solid state lighting revolution has brought tremendous benefits of greater light source efficiency, longevity and new applications. While most major lighting applications have seen over 50% replacement of conventional light sources, there is tremendous opportunity in new ideas for better spectral engineering, and where, when and how we use light. Digital lighting is the next wave in light source technology where close coupling of LEDs with electronics and optics enables energy-efficient and versatile lighting solutions across different sectors. Automotive lighting is being enhanced with adaptive lighting systems, improving safety. Mobile phones now boast adaptive flash for better imaging. General Illumination has the potential for a significant shift towards smart and connected systems, optimizing energy usage by delivering the light dynamically, thus mitigating problems associated with light pollution and enhancing our well-being. MicroLED displays promise higher resolution, increased brightness, efficiency and never before possible compact light engines. We will talk about the latest Lumileds technologies enabling digital light sources and new applications.

The goal of this paper is to study the link between the solution to an Hamilton-Jacobi (HJ) equation and the solution to a Scalar Conservation Law (SCL) on a special network. When the equations are posed on the real axis, it is well known that the space derivative of the solution to the Hamilton-Jacobi equation is the solution to the corresponding scalar conservation law. On networks, the situation is more complicated and we show that this result still holds true in the convex case on a 1:1 junction. The correspondence between solutions to HJ equations and SCL on a 1:1 junction is done showing the convergence of associated numerical schemes. A second direct proof using semi-algebraic functions is also given. Here a 1:1 junction is a simple network composed of two edges and one vertex. In the case of three edges or more, we show that the associated HJ germ is not a L 1-dissipative germ, while it is the case for only two edges. As an important byproduct of our numerical approach, we get a new result on the convergence of numerical schemes for scalar conservation laws on a junction. For a general desired flux condition which is discretized, we show that the numerical solution with the general flux condition converges to the solution of a SCL problem with an effective flux condition at the junction. Up to our knowledge, in previous works the effective condition was directly implemented in the numerical scheme. In general the effective flux condition differs from the desired one, and is its relaxation, which is very natural from the point of view of Hamilton-Jacobi equations. Here for SCL, this effective flux condition is encoded in a germ that we characterize at the junction.

Abstract Developable mechanisms provide unparalleled compactness and deployability. This paper explores the kinematic behavior of developable mechanisms that conform to regular cylindrical surfaces. Equations that define these mechanisms within mechanism synthesis are provided and compared with path and motion synthesis tasks for traditional four-bar mechanisms. The design implications, limitations, and opportunities associated with regular cylindrical developable mechanisms are discussed through the lens of both an analytical and graphical method.

Abstract The simulation of a novel drone‐based near‐field (NF)/far‐field (FF) antenna measurement system enabling the reconstruction of Antenna Under Test (AUT) phase and the true location of the untethered drone using multiple land‐based reference antennas is described. The mathematical approach follows the principle used within Global Positioning System (GPS) position and time recovery. Conceptually, the satellites are replaced by ground‐based reference antennas of known location, the user location is now the drone location and the user clock offset is replaced by the unknown AUT phase radiated at the angle subtended between the AUT and drone location. This addresses the need for drone‐based NF/FF antenna measurement of large in situ VHF/UHF antenna arrays plus the need to measure the installed performance of microwave antennas on structures such as buildings, aircraft and ships. To assess the viability, a computer simulation of the measurement system is constructed and its performance is analysed in terms of the accuracy of reconstruction of the AUT phase and true drone location, as well as the NF/FF radiation pattern accuracy in terms of the equivalent multipath level (EMPL). An example measurement ‘range’, comprising AUT location and six fixed reference antennas, demonstrates a wide AUT operating bandwidth of (0.5–2) GHz, with EMPL &lt; −50 dB over the forward hemisphere.