Exceeding probability analysis for rail of high-speed railway under seismic excitations

Purpose–The smoothness of the high-speed railway(HSR)on the bridge may exceed the allowable standard when an earthquake causes vibrations for HSR bridges,which may threaten the safety of running trains.Indeed,few studies have evaluated the exceeding probability of rail displacement exceeding the allowable standard.The purposes of this article are to provide a method for investigating the exceeding probability of the rail displacement of HSRs under seismic excitation and to calculate the exceeding probability.Design/methodology/approach–In order to investigate the exceeding probability of the rail displacement under different seismic excitations,the workflow of analyzing the smoothness of the rail based on incremental dynamic analysis(IDA)is proposed,and the intensity measure and limit state for the exceeding probability analysis of HSRs are defined.Then a finite element model(FEM)of an assumed HSR track-bridge system is constructed,which comprises a five-span simply-supported girder bridge supporting a finite length CRTS II ballastless track.Under different seismic excitations,the seismic displacement response of the rail is calculated;the character of the rail displacement is analyzed;and the exceeding probability of the rail vertical displacement exceeding the allowable standard(2mm)is investigated.Findings–The results show that:(1)The bridge-abutment joint position may form a step-like under seismic excitation,threatening the running safety of high-speed trains under seismic excitations,and the rail displacements at mid-span positions are bigger than that at other positions on the bridge.(2)The exceeding probability of rail displacement is up to about 44%when PGA 50.01g,which is the level-five risk probability and can be described as’very likely to happen’.(3)The exceeding probability of the rail at the mid-span positions is bigger than that above other positions of the bridge,and the mid-span positions of the track-bridge system above the bridge may be the most hazardous area for the running safety of trains under seismic excitation when high-speed trains run on bridges.Originality/value–The work extends the seismic hazardous analysis of HSRs and would lead to a better understanding of the exceeding probability for the rail of HSRs under seismic excitations and better references for the alert of the HSR operation.

Generating Proton Beams Exceeding 10 MeV Using High Contrast 60TW Laser

A prototype of a laser driven proton accelerator is built at Peking University. Protons exceeding IOMeV are accelerated from micrometer-thick aluminum targets irradiated by tightly focused laser pulse with 1.8 J energy and 30fs duration. The beam energy spectrum and charge distribution are measured by a Thomson parabola spectrometer and radiochromic fihn stacks. The sensitivity of proton cut-off energy to the focusing of the laser beam, the pulse duration, and the foil thickness are systematically investigated in the experiments. Stable proton beams have been produced with an optimized parameter set, providing a cornerstone for the future applications of laser accelerated protons.

Iron-based Fischer-Tropsch Synthesis Catalyst Achieves an Alcohol Selectivity Exceeding 60%

The key project'Nano-scale catalyst and related process research and development activity for high-efficiency synthesis of mixed lower alcohols from syngas'undertaken by the Shanghai Senior Research Institute of CAS has passed the acceptance tests by the expert group organized by the Shanghai Science and Technology Commission.

China's Power Generating Capacity Exceeding 200 GW

Shi Dazhen, Minister of the Power Industry, has announced that China’s power Construction had developed to a new level, exceeding 200 GW. He said that China’s power generating capacity reached 100 GW in 1987 and 199.9 GW at the end of last year. As another two 60,000 kilowatts of power generation units went into operation in March, this year, power generating capacity reaches 200 GW in only seven years. Such a construction scale and

Exceeding Expectations

As the escalating trade dispute between China and the United States casts a shadow over the world＇s two largest economies andthe global economy at large, the much an ticipated Chinese economic figures for the first half of the year offer some certainty of China＇s economic resilience and sustainability.

D-band 4600 m wireless transmission with rates exceeding 100 Gbit/s based on photonics aided technologies

With the rise of emerging applications such as artificial intelligence(AI),virtual reality(VR), and short videos, the number of Internet terminals has increased dramatically [1]. According to the Cisco Annual Traffic Survey Report, annual traffic is growing at a compound annual growth rate of 20%[2]. To meet exploding growth in traffic demands, researchers have turned their attention to license-free high-band millimeter wave(MMW), such as W-band(75–110 GHz), D-band(110–170 GHz), and terahertz band(THz) [3,4].

Mechanical robust and self-healing flexible perovskite solar cells with efficiency exceeding 23%

Flexible perovskite solar cells(f-PSCs) have experienced rapid advancements due to the light-weight, flexibility, and solution processability of the perovskite materials, which prompted the power conversion efficiency(PCE) to 24.08%. However, f-PSCs still face challenges in terms of mechanical and environmental stability. This is primarily due to their inherent brittleness, the presence of residual tensile strain, and the high density of defects along the boundaries of perovskite grains. To this end, we carefully developed a cross-linkable elastomers 3-[(3-acrylamidopropyl)dimethylammonium] propanoate(ADP) with electrostatic dynamic bond, which could be in-situ cross-linked and coordinate with [Pb I6]4-to regulate the crystallization process of perovskite. The cross-linked elastomers attached to the perovskite grain boundaries could release the remaining tensile strains and mechanical stresses, leading to enhanced stability and flexibility of the f-PSCs. More importantly, the electrostatic interaction between positive and negative groups of cross-linked elastomers and hydrogen bond formation between N–H and C=O accelerate the cross-linking of ADP, endowing the flexible perovskite films with self-healing ability under mild treating conditions(60 °C for 30 min). As a result, the device achieves a remarkable PCE of 23.53%(certified 23.16%). Additionally, the device exhibits impressive mechanical sustainability and durability, retaining over 90% of initial PCE even after undergoing8,000 bending cycles.

Gallium nitride blue laser diodes with pulsed current operation exceeding 15 W in optical output power

Since Shuji Nakamura first demonstrated the nitride laser in 1996[1],the domain of semiconductor laser technology has undergone a period of remarkable growth[2,3].Al In Ga N-based diode lasers(LDs)have proven their exceptional capabilities across a spectrum of pivotal applications,including high-density data storage,laser displays,laser lighting,and quantum technology[4].

Hole transport layer-free inverted perovskite solar cells with power conversion efficiency exceeding 25%and much improved stability

Organic-inorganic hybrid perovskites possess a unique combination of excellent electronic and photoelectrochemical properties that can be readily tailored by partial or complete substitution of their constituent elements owing to their nonclose packing anion lattice[1,2].Perovskite solar cells(PSCs)employing hybrid perovskites as an active layer have seen rapid improvements and have achieved high power conversion efficiencies(PCEs)now exceeding 25%[2].

Is it worth already in the first step exceeding the 3-g protein limit for the oral food challenge for food protein-induced enterocolitis syndrome?

To the editor:Food protein-induced enterocolitis syndrome(FPIES)is a non-immunoglobulin E-mediated food allergy that is characterized by repetitive vomiting within 1-4 h of eating the trigger food and may be associated with lethargy,pallor,and diarrhea.The diagnosis is in most cases anamnestic.1 In a few cases,it is necessary to perform the oral food challenge(OFC).

Harnessing the power of pericytes and hypoxia-inducible factor-1 to modulate stroke outcome

The human brain has exceedingly high metabolic demands.The cerebral vasculature has the critical task of providing sufficient blood supply to meet this demand.The sudden interruption of blood flow to the brain,as observed during ischemic stroke,results in acute neurological injury with devastating consequences-a high rate of adult disability and death.Ischemic stroke is thus a vascular disorder with a dramatic neurological impact.There is an urgent need for more effective disease management to combat stroke as current treatment paradigms,focusing on vascular recanalization and neuroprotection,have only limited clinical success.Since accumulating data suggests successful long-term neuroprotection is unlikely to be achievable without a functional microvascular network,strategies that reduce endothelial dysfunction could be indispensable.Encouragingly,very recent evidence highlighted herein suggests protecting the humble pericyte may be a new approach to reaching this goal.

A statistical study on the correlation between sporadic Ca+layer and Es in Beijing(40.5°N,116°E)

From April 2020 to June 2022,a Ca+lidar with dual-wavelength and narrow-band emitting lasers utilizing all-solid-state technology was employed to conduct observations in Beijing(40.41°N,116.01°E)for a total duration of 1797.79 hours over 280 nights.A total of 286 sporadic Ca+layers were observed,with heights ranging from 88 to 120 km and densities varying from 5.33 to 2200 cm^(-3).We simultaneously observed the ionosonde,located 28 km from the lidar,and found a correlation of 61.89%between the sporadic Ca+layer and the sporadic E layer.When the sporadic Ca+layer has a downward phase trend,there is a correlation of 76.84%.By excluding the influence of ionosonde sensitivity,we focus only on calcium ions that have a density exceeding 140 cm^(-3),which exhibit a correlation of82.25%.Above 100 km,the correlation significantly increases,reaching approximately 90%.Furthermore,the correlation between the sporadic Ca+layer and the sporadic E layer is particularly noticeable during the summer season,reaching around 90%.This phenomenon can be attributed to the variations in metal ions that occur during different seasons.

Ten Changes in the Cosmetics Industry in 2023

New life was accompanied by death,consumption upgrading was accompanied by consumption downgrading,triumphant advancement was accompanied by steady retreatin.In 2023,magic realist dramas were played in China’s cosmetics industry one after another.That year,the domestic brands set off a prologue of counterattacking foreign brands with“Proya winning the first place in Tmall’s Double Eleven promotion for 2023”as a landmark event.That year,South Korean cosmetics,Japanese cosmetics and major European and American brands“became depressed”collectively,and the acutely turbulent list could hardly conceal the injury of“being defeated”and“being unsalable”.That year,Proya and Botanee achieved a rapid growth,and the first domestic cosmetics group with the annual operating revenue exceeding 8.0 billion yuan was coming into being.

Current Status of Brazil’s New Energy and Green Low-carbon Practices in Deep-water Oil Fields

Brazil possesses abundant new energy resources such as solar energy,wind energy,and biomass energy,and is at the forefront of the world in the development and utilization of new energy,becoming a pioneer in energy transition and low-carbon development.Renewable energy accounts for nearly half of Brazil’s primary energy consumption,with the share in the power sector exceeding 75%.Brazil has achieved its carbon peak and is still actively promoting carbon and emission further reduction and the development of new energy.

Current Status and Prospects of China’s Natural Gas Industry

In 2023,China’s natural gas sector experienced robust growth in both supply and demand dynamics,as consumption regained an upward trend,reaching 394.53 billion m3,reflecting a 7.6%year-on-year surge.Domestic gas production and reserves persistently progressed,hitting a production volume of 228.84 billion m3 and achieving a seven-year consecutive increment exceeding 10 billion m^(3).After an initial sharp decline,imported natural gas rebounded to record growth;the combined import volume of pipeline gas and LNG climbed to 163.92 billion m^(3),a notable 11.3%rise compared to the previous year.As China’s policies for stable economic growth are further entrenched in 2024,the macroeconomic recovery is anticipated to continue.Bolstered by the dual-carbon strategy and the transformative policies targeting high-energy-consuming industries,the natural gas market is expected to sustain its rapid expansion,with estimated growth in demand ranging between 5.8%and 7.1%.

On Cloud Nine Karamay's leading AI-empowered cloud computing

The benchmark of Xinjiang's computing power is determined by Karamay,known as an"oil city."With an impressive annual crude oil output exceeding 16 million tons,Karamay is now exploiting computing power,the"new black gold"of the artificial intelligence (AI) era.Since the Karamay Cloud Computing Industrial Park officially opened in 2013,it has attracted more than 150 companies including three that are publicly listed on the New Third Board.

SCIENCE AND TECHNOLOGY

Deep-Earth Borehole Drilling Project Achieves 10,000-Meter Milestone China has achieved a significant breakthrough in deep-Earth exploration with the drilling of a superdeep borehole in Xinjiang Uygur Autonomous Region exceeding the 10,000-meter mark,making it the deepest vertical well in Asia,even though the project as a whole is not yet completed.Amid the continuous humming of the drilling rig,the number on an electronic screen in the command center reached the milestone of 10,000 meters at 2:48 p.m.on March 4.More than 100 workers on site,who had eagerly anticipated this moment,erupted into cheers.Located in the hinterland of the Taklimakan Desert in the Tarim Basin,Shenditake 1 is a scientific exploratory borehole with a designed depth of 11,100 meters.In addition to searching for oil and gas resources,it is also tasked with pursuits such as exploring the evolution of Earth.

In Brief

The annual oil and gas output of Fuman Oilfield,China's largest ultra-deep oilfield,exceeded 4 million tons,On December 29,2023,the annual oil and gas production of Fuman Oilfield,China's largest ultra-deep oilfield,exceeded 4 million tons,reaching a new peak of 4.036 million tons.This marks another new advancement in the large-scale and efficient development of ultra-deep and complex oil and gas reservoirs in CNPC Tarim Oilfield,creating a new growth pole for increasing reserves and production of crude oil in China.Fuman Oilfield is the oilfield with the largest number of ultra-deep wells of over 8,000 meters in China,and more than 110 wells have a depth exceeding 8,o00 meters and are defined as Underground Everest".In 2019,the annual oil and gas production of Fuman Oilfield increased from 20,000 tons at the beginning of development to 1.08 million tons.

Exciton diffusion exceeding 1μm:run,exciton,run!

Exciton diffusion lengths reaching the micrometer length scale have long been desired in solution-processed semiconductors but have remained unattainable using conventional materials to date.Now halide perovskite nanocrystal films show unprecedented exciton migration with diffusion lengths approaching 1μm owing to the efficient combination of radiative and nonradiative energy transfer.

Probability Distribution Characteristics of Strong Nonlinear Waves Under Typhoon Conditions in the Northern South China Sea

The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields under extreme sea states. The model, integrating the ST6 source term, is validated against observed data, demonstrating its credibility. The spatial distribution of the occurrence probability of strong nonlinear waves during typhoons is shown, and the waves in the straits and the northeastern part of the South China Sea show strong nonlinear characteristics. The high-order spectral model HOS-ocean is employed to simulate the random wave surface series beneath five different platform areas. The waves during the typhoon exhibit strong nonlinear characteristics, and freak waves exist. The space-varying probability model is established to describe the short-term probability distribution of nonlinear wave series. The exceedance probability distributions of the wave surface beneath different platform areas are compared and analyzed. The results show that with an increase in the platform area, the probability of a strong nonlinear wave beneath the platform increases.