Performance of the CMS muon trigger system in proton-proton collisions at √s = 13 TeV

The muon trigger system of the CMS experiment uses a combination of hardware and software to identify events containing a muon. During Run 2 (covering 2015-2018) the LHC achieved instantaneous luminosities as high as 2 × 10 cm s while delivering proton-proton collisions at √s = 13 TeV. The challenge for the trigger system of the CMS experiment is to reduce the registered event rate from about 40 MHz to about 1 kHz. Significant improvements important for the success of the CMS physics program have been made to the muon trigger system via improved muon reconstruction and identification algorithms since the end of Run 1 and throughout the Run 2 data-taking period. The new algorithms maintain the acceptance of the muon triggers at the same or even lower rate throughout the data-taking period despite the increasing number of additional proton-proton interactions in each LHC bunch crossing. In this paper, the algorithms used in 2015 and 2016 and their improvements throughout 2017 and 2018 are described. Measurements of the CMS muon trigger performance for this data-taking period are presented, including efficiencies, transverse momentum resolution, trigger rates, and the purity of the selected muon sample. This paper focuses on the single- and double-muon triggers with the lowest sustainable transverse momentum thresholds used by CMS. The efficiency is measured in a transverse momentum range from 8 to several hundred GeV

Rapid and Energy-Efficient Manufacturing of Thermoset Prepreg Via Localized In-Plane Thermal Assist (LITA) Technique

Prepregs are in demand for large production by the composites manufacturing industry to improve the mechanical properties of the load-bearing structural parts. The current prepreg manufacturing is confronted with inadequate resin impregnation, high energy costs, and safety concerns. To address those challenges, in this paper, we proposed a novel thermoset prepreg fabrication strategy that utilizes viscosity controlled by thermal gradient as well as gravity to achieve fast and energy-efficient manufacturing of thermoset prepreg. The concept is based on the localized in-plane thermal assist (LITA) technique, which uses a dynamic capillary effect to induce the wicking of thermoset resins in carbon fibers. This work demonstrated that a bench-scale continuous production of thermoset prepreg with carbon fiber tows can be achieved, and results show that the produced prepreg is B-staged, with the degree of curing as 13.9%. Our calculation suggests that the LITA prepreg fabrication method could save 63.56% of energy compared to the traditional prepreg fabrication methods, and increase the production rate by 133.28% compared to the traditional hot-melt prepreg fabrication method. The LITA prepreg method represents an efficient and eco-friendly composite manufacturing technology to outperform the state-of-the-art energy-intensive prepreg fabrication methods

Rapid and Energy-Efficient Manufacturing of Thermoset Prepreg Via Localized In-Plane Thermal Assist (LITA) Technique

Prepregs are in demand for large production by the composites manufacturing industry to improve the mechanical properties of the load-bearing structural parts. The current prepreg manufacturing is confronted with inadequate resin impregnation, high energy costs, and safety concerns. To address those challenges, in this paper, we proposed a novel thermoset prepreg fabrication strategy that utilizes viscosity controlled by thermal gradient as well as gravity to achieve fast and energy-efficient manufacturing of thermoset prepreg. The concept is based on the localized in-plane thermal assist (LITA) technique, which uses a dynamic capillary effect to induce the wicking of thermoset resins in carbon fibers. This work demonstrated that a bench-scale continuous production of thermoset prepreg with carbon fiber tows can be achieved, and results show that the produced prepreg is B-staged, with the degree of curing as 13.9%. Our calculation suggests that the LITA prepreg fabrication method could save 63.56% of energy compared to the traditional prepreg fabrication methods, and increase the production rate by 133.28% compared to the traditional hot-melt prepreg fabrication method. The LITA prepreg method represents an efficient and eco-friendly composite manufacturing technology to outperform the state-of-the-art energy-intensive prepreg fabrication methods

Stretchable One-Dimensional Conductors for Wearable Applications.

Continuous, one-dimensional (1D) stretchable conductors have attracted significant attention for the development of wearables and soft-matter electronics. Through the use of advanced spinning, printing, and textile technologies, 1D stretchable conductors in the forms of fibers, wires, and yarns can be designed and engineered to meet the demanding requirements for different wearable applications. Several crucial parameters, such as microarchitecture, conductivity, stretchability, and scalability, play essential roles in designing and developing wearable devices and intelligent textiles. Methodologies and fabrication processes have successfully realized 1D conductors that are highly conductive, strong, lightweight, stretchable, and conformable and can be readily integrated with common fabrics and soft matter. This review summarizes the latest advances in continuous, 1D stretchable conductors and emphasizes recent developments in materials, methodologies, fabrication processes, and strategies geared toward applications in electrical interconnects, mechanical sensors, actuators, and heaters. This review classifies 1D conductors into three categories on the basis of their electrical responses: (1) rigid 1D conductors, (2) piezoresistive 1D conductors, and (3) resistance-stable 1D conductors. This review also evaluates the present challenges in these areas and presents perspectives for improving the performance of stretchable 1D conductors for wearable textile and flexible electronic applications

Thermally Conductive 3D-Printed Carbon-Nanotube-Filled Polymer Nanocomposites for Scalable Thermal Management

Thermal transportation in a preferred direction is desirable and important for addressing thermal management issues. With the merits of high thermal conductivity, good chemical stability, and desirable mechanical properties, carbon nanotubes (CNTs) have a great potential for wide applications in heat dissipation devices. The combination of 3D printing and CNTs can enable unlimited possibilities for hierarchically aligned structural programming. We report the formation of through-plane aligned multiwalled CNT (MWCNT)-filled polylactic acid (PLA) nanocomposites by 3D printing. The as-printed vertically (or through-plane) aligned structure demonstrates a through-plane thermal conductivity (k⊥) of ∼0.575 W/(mK) at 20 wt % MWCNT content, which is around 2.64 times that of a horizontally aligned structure (∼0.218 W/(mK)) and around 5.87 times that of neat PLA (∼0.098 W/(mK)) at 35 °C. Infrared thermal imaging performed on 3D-printed MWCNT/PLA heat sink verified the superior performance of the nanocomposite compared to that of the matrix polymer. In this study, we achieved the manufacturing of MWCNT/PLA with a high filler loading and a significant improvement in thermal conductivity simultaneously. This work paves the way to develop 3D-printed carbon filler-reinforced polymer composites for thermal-related applications such as heat sinks or thermal radiators

Inserting Insulating Barriers Into Conductive Particle Channels: A New Paradigm For Fabricating Polymer Composites With High Dielectric Permittivity and Low Dielectric Loss

A longstanding challenge in fabricating high dielectric polymer composite is how to rationalize structure design to improve dielectric permittivity while minimizing dielectric loss. Typically, adding conductive particles in to the composite often leads to an increase in the dielectric loss caused by leakage current due to ‘insulator-conductor’ transition at the percolation threshold. This work presents a strategy for simultaneously assembling conductive and insulating particles to form chainlike structures, based on dipole-dipole interactions induced by electric fields. Specifically, insulating barium titanate (BaTiO3) particles can be subtly embeded in the conductive graphite channels to serve as barriers. The formation of such morphology plays an important role for balancing the high dielectric permittivity and relatively low dielectric loss for conductive fillers/polymer composite systems. With only 2.5 wt% graphite, the dielectric permittivity can be enhanced significantly upon electric field induced assembly, while the dielectric loss also inevitably increases to 396. By incorporating additional 5 wt% BaTiO3 (barriers), we are able to reduce the dielectric loss to as low as 0.19 while the dielectric permittivity still remains relatively high (73.5). This work provides a critical material design concept for high-performance flexible dielectric materials based on creating barriers through the assistance of electric fields in ternary composites, which prevents the generation of leakage current between conductive fillers interfaces

Electric Field-Induced Assembly and Alignment of Silver-Coated Cellulose for Polymer Composite Films With Enhanced Dielectric Permittivity and Anisotropic Light

Multifarious wearable electronics with flexible touch screens have been invented for extensive outdoor activities. One challenge associated with these wearable electronics is the development of materials with both high dielectric permittivity and anisotropic light transmission, which is responsible for high touch sensitivity and screen peep-proof protection, respectively. Herein, we demonstrated a scalable approach for assembling and aligning anisotropic cellulose in a polymer matrix through the thickness direction via the assistance of an electric field to address this challenge. The alignment of silver-coated fibrillated celluloses in the polymer matrix not only significantly increases dielectric permittivity but also effectively enhances optical anisotropy. The impact of alignment degree and filler content on the dielectric and optical properties of polymer composite films has been systematically studied. The kinetics and aligning mechanisms of silver-coated fibrillated celluloses are revealed by in situ optical microscope images while an electric field is applied. We believe that this study provides a facile strategy to enhance both dielectric permittivity and optical anisotropy of polymer composite films by the alignment of embedding nanoparticles via an AC electric field, which is essential for future flexible electronics and display technology

Three-Dimensional Printable High-Temperature and High-Rate Heaters

High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important

Three-Dimensional Printable High-Temperature and High-Rate Heaters

High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important