Determination of short circuit location in the electric railway traction

This article discusses the problem of improving the accuracy of determining the location of a short circuit in the AC railways traction networks. Finding a short circuit can take several hours. An urgent task is reducing the time to search for a fault location. The purpose of the study is to develop a method that increases the accuracy of determining the location of a short circuit in AC traction networks. The method is based on computer modeling of inhomogeneities in the structure of the traction network and the arc. The proposed method makes it possible to take into account the arc resistance. The method was tested on the traction network active section. The error of the method is 200-300 meters. The method can find practical application in the work of dispatchers.

Progressing-Cavity-Pump Configuration Addresses Operational Challenges

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201130, “Novel Progressing-Cavity-Pump Configurations Address Operational Challenges,” by Lonnie Dunn, SPE, Ryan Rowan, and Abhishek Prakash, Lifting Solution, et al., prepared for the 2020 SPE Virtual Artificial Lift Conference and Exhibition-Americas, 10-12 November. The paper has not been peer reviewed. While downhole progressing-cavity-pump (PCP) designs provide options for end users, the numerous products available, combined with a lack of industry standardization, can make selection and application challenging. The complete paper provides an overview of the development of a PCP concept and implementation, which is not included in this synopsis, and then summarizes two novel PCP configurations deployed to address specific operational challenges. Design and Manufacturing, Configuration 1 A novel PCP configuration was developed from phased design trials and experience in cold heavy-oil production with sand (CHOPS) wells. This configuration uses a modified rotor to create alternating sections of contact and noncontact within a conventional stator (Fig. 1). The rotor is landed in the stator and operated until there is a performance decline. Then, the rotor is repositioned to move the active section of the rotor into the areas of the stator where there originally was no contact and, as such, normally no associated damage. Keeping the length of the alternating sections short simplifies the surface rotor positioning process, allowing it to be performed riglessly. The main benefit of this is that, rather than having to pull the rod string and run a different rotor, the same rotor is used and repositioned through lifting of the rod string at surface.

Nanorods with multidimensional optical information beyond the diffraction limit

Precise design and fabrication of heterogeneous nanostructures will enable nanoscale devices to integrate multiple desirable functionalities. But due to the diffraction limit (~200 nm), the optical uniformity and diversity within the heterogeneous functional nanostructures are hardly controlled and characterized. Here, we report a set of heterogeneous nanorods; each optically active section has its unique nonlinear response to donut-shaped illumination, so that one can discern each section with super-resolution. To achieve this, we first realize an approach of highly controlled epitaxial growth and produce a range of heterogeneous structures. Each section along the nanorod structure displays tunable upconversion emissions, in four optical dimensions, including color, lifetime, excitation wavelength, and power dependency. Moreover, we demonstrate a 210 nm single nanorod as an extremely small polychromatic light source for the on-demand generation of RGB photonic emissions. This work benchmarks our ability toward the full control of sub-diffraction-limit optical diversities of single heterogeneous nanoparticles.

Nanobarcodes with multidimensional optical information beyond diffraction limit

Precise design and fabrication of heterogeneous nanostructures will enable nanoscale devices to integrate multiple desirable functionalities. But due to the diffraction limit (~200 nm), the optical uniformity and diversity within the heterogeneous functional nanostructures are hardly controlled and characterized. Here we report a set of nanobarcodes, each optically active section has its unique nonlinear responses to donut illumination patterns, so that one can discern each unit with super resolution. To achieve this, we first realized an approach of highly controlled epitaxial growth and produced a range of one-dimensional heterogeneous structures. Each section along the nanorod structure display tunable upconversion emissions, in four optically orthogonal dimensions, including colour, lifetime, excitation wavelength, and power dependency. Moreover, we demonstrated a 210 nm single nanorod as the smallest polychromatic light source for the on-demand generation of RGB photonic emissions. Remarkably, within a space of 50 nm, only 1/20th of the excitation wavelength, multiple codes can be successfully coded and decoded in 4 optical dimensions. This precision control enables the fabrication of super capacity geometrical barcodes with theoretical coding capacity up to (24-1)4. This work benchmarks our new ability towards the full control of sub-diffraction-limit optical diversities of single heterogeneous nanoparticles.

Peristaltic Pumping and Propulsion With Distributed Piezocomposite Actuators

This paper investigates the feasibility of a soft-structure peristaltic pumping and propulsion concept with distributed self-contained piezocomposite actuators. The peristaltic propulsion concept is analogous to various natural and synthetic mechanisms such as: (i) pulsed jet propulsion and thrust vectoring observed in squids, and (ii) operation principle of multi-phase linear electromagnetic motors. This paper proposes a propulsion system involving a series of active soft cymbal-like segments that are connected with passive soft connective segments. The active sections of the channel have distributed piezocomposite actuators, and these embedded self-contained devices enable the active section of the channel to expand and contract much like the muscular hydrostatic mantle of squids. A series of phased excitations in expansion and contraction applied to different active segments of the channel create a traveling wave along the axis of the channel, which in return “propels” the fluid in one direction. A tubular aperture with vectoring capabilities, similar to the rotating funnel of squids, is also possible. The paper presents feasibility of the concept with theoretical and experimental analyses.