In the 2015 review paper ‘Petawatt Class Lasers Worldwide’ a comprehensive overview of the current status of high-power facilities of ${>}200~\text{TW}$ was presented. This was largely based on facility specifications, with some description of their uses, for instance in fundamental ultra-high-intensity interactions, secondary source generation, and inertial confinement fusion (ICF). With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification (CPA), which made these lasers possible, we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed. We are now in the era of multi-petawatt facilities coming online, with 100 PW lasers being proposed and even under construction. In addition to this there is a pull towards development of industrial and multi-disciplinary applications, which demands much higher repetition rates, delivering high-average powers with higher efficiencies and the use of alternative wavelengths: mid-IR facilities. So apart from a comprehensive update of the current global status, we want to look at what technologies are to be deployed to get to these new regimes, and some of the critical issues facing their development.

The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.

The development of highly active and durable inexpensive electrocatalysts for hydrogen evolution reaction (HER) is still a formidable challenge. Herein, an ordered hexagonal-closed-packed (hcp)-Ru nanocrystal coated with a thin layer of N-doped carbon (hcp-Ru@NC) was fabricated through the thermal annealing of polydopamine (PDA)-coated Ru nanoparticle (RuNP@PDA). As an alternative to Pt/C catalyst, the hcp-Ru@NC nanocatalyst exhibited the small overpotential of 27.5 mV at a current density of 10 mA cm −2 , as well as long-term stability for HER in acid media. Interestingly, the HER performance of hcp-Ru is highly dependent on its crystallinity. The calculation from density functional theory (DFT) revealed that the difference in HER activity over various exposed surface causes the crystallinity-dependent property of hcp-Ru. The results provided clues to guide the design of Ru-based inexpensive HER electrocatalyst.

Magnetic reconnection is a process by which oppositely directed magnetic field lines passing through a plasma undergo dramatic rearrangement, converting magnetic potential into kinetic energy and heat 1,2. It is believed to play an important role in many plasma phenomena including solar flares 3,4 , star formation 5 and other astrophysical events 6 , laser-driven plasma jets 7-9 , and fusion plasma instabilities 10. Because of the large differences of scale between laboratory and astrophysical plasmas, it is often difficult to extrapolate the reconnection phenomena studied in one environment to those observed in the other. In some cases, however, scaling laws 11 do permit reliable connections to made, such as the experimental simulation of interactions between the solar wind and the Earth's magnetosphere 12. Here we report well-scaled laboratory experiments that reproduce loop-top-like X-ray source emission by reconnection outflows interacting with a solid target. Our experiments exploit the mega-gauss-scale magnetic field generated by interaction of a high-intensity laser with a plasma to reconstruct a magnetic reconnection topology similar to that which occurs in solar flares. We also identify the separatrix and diffusion regions associated with reconnection in which ions become decoupled from electrons on a scale of the ion inertial length. A major objective of laboratory astrophysics is to simulate the fundamental nature of astrophysical plasma physics processes in a laboratory environment so that certain astrophysical phenomenon can be studied in a controlled manner 13. High energy density facilities, such as high-powered lasers and Z-pinches, can provide such opportunities 14 , for example, direct measurements of opacity 15 , equations of state 16 , and photoionized plasmas 17,18 , as well as the similarity of physics, such as certain hydrodynamic phenomena of jets 19 and shocks 20 where a scaling law between astrophysical and laboratory plasma systems can be applied. As a fundamental cause of many plasma energy conversion processes, magnetic reconnection (MR) is certainly a high priority of such studies. Masuda et al. 21 observed the loop-top X-ray source in solar flares using the YOHKOH satellite and proposed that two antiparallel magnetic fields were merged above an arcade of closed loops as outflow jets from the reconnection point collided with high-density plasmas on the loop to produce a hot X-ray region. Ultraviolet 22 and X-ray 23,24 observations of plasma

A facile surfactant-free process is introduced to prepare multifunctional polypropylene (PP) nanocomposites filled with highly dispersed Fe@Fe2O3 core@shell nanoparticles (NPs). Transmission electron microscopy (TEM) observations confirm the formation of uniform NPs in the PP matrix and the particle size increases with increasing the particle loading. The melt rheology measurements show an obvious change in the frequency dependent storage modulus (G′), loss modulus (G′′) and complex viscosity (η * ) particularly at low frequencies. These changes are often related to the filler “percolation threshold”, which has also been verified in the sharp change of electrical resistance and dielectric permittivity of these nanocomposites in higher particle loadings. The continuous decrease in the resistivity with increasing filler loading from 5 wt % to 20 wt % demonstrates the structural transition of the nanocomposites. The monotonic increase in the dielectric permittivity with increasing particle loadings combined with the direct evidence from the TEM observations indicate that the NPs are well separated and uniformly dispersed in the polymer matrix. Thermal gravimetric analysis (TGA) results reveal a surprisingly high enhancement of the thermal stability by ∼120 °C in air due to the oxygen trapping effect of the NPs and the polymer–particle interfacial interaction. The differential scanning calorimetry (DSC) results show that the crystalline temperature (T c ) of the nanocomposites is reduced by 16–18 °C as compared to that of PP, while the melting temperature (T m ) almost maintains the same. The nanocomposites is found to be soft ferromagnetic at room temperature.

As an important safety critical cyber-physical system (CPS), the braking system is essential to the safe operation of the electric vehicle. Accurate estimation of the brake pressure is of great importance for automotive CPS design and control. In this paper, a novel probabilistic estimation method of brake pressure is developed for electrified vehicles based on multilayer Artificial Neural Networks (ANN) with Levenberg-Marquardt Backpropagation (LMBP) training algorithm. Firstly, the highlevel architecture of the proposed multilayer ANN for brake pressure estimation is illustrated. Then, the standard backpropagation (BP) algorithm used for training of the feedforward neural network (FFNN) is introduced. Based on the basic concept of backpropagation, a more efficient training algorithm of LMBP method is proposed. Next, real vehicle testing is carried out on a chassis dynamometer under standard driving cycles. Experimental data of the vehicle and the powertrain systems are collected, and feature vectors for FFNN training collection are selected. Finally, the developed multilayer ANN is trained using the measured vehicle data, and the performance of the brake pressure estimation is evaluated and compared with other available learning methods. Experimental results validate the feasibility and accuracy of the proposed ANN-based method for braking pressure estimation under real deceleration scenarios.

Sustainable development in the building sector requires the integration of energy efficiency and renewable energy utilization in buildings. In recent years, the concept of net zero energy buildings (NZEBs) has become a potential plausible solution to improve efficiency and reduce energy consumption in buildings. To achieve an NZEB goal, building systems and design strategies must be integrated and optimized based on local climatic conditions. This paper provides a comprehensive review of NZEBs and their current development in hot and humid regions. Through investigating 34 NZEB cases around the world, this study summarized NZEB key design strategies, technology choices and energy performance. The study found that passive design and technologies such as daylighting and natural ventilation are often adopted for NZEBs in hot and humid climates, together with other energy efficient and renewable energy technologies. Most NZEB cases demonstrated site annual energy consumption intensity less than 100 kW-hours (kWh) per square meter of floor space, and some buildings even achieved "net-positive energy" (that is, they generate more energy locally than they consume). However, the analysis also shows that not all NZEBs are energy efficient buildings, and buildings with ample renewable energy adoption can still achieve NZEB status even with high energy use intensity. This paper provides in-depth casestudy-driven analysis to evaluate NZEB energy performance and summarize best practices for high performance NZEBs. This review provides critical technical information as well as policy recommendations for net zero energy building development in hot and humid climates.

Anomalous observations using the fast ignition for laser driven fusion energy are interpreted and experimental and theoretical results are reported which are in contrast to the very numerous effects usually observed at petawatt-picosecond laser interaction with plasmas. These anomalous mechanisms result in rather thin blocks (pistons) of these nonlinear (ponderomotive) force driven highly directed plasmas of modest temperatures. The blocks consist in space charge neutral plasmas with ion current densities above 1010A∕cm2. For the needs of applications in laser driven fusion energy, much thicker blocks are required. This may be reached by a spherical configuration where a conical propagation may lead to thick blocks for interaction with targets. First results are reported in view of applications for the proton fast igniter and other laser-fusion energy schemes.