Search

A light source with narrowband, sufficient brightness, and low spatial coherence is required for certain applications such as optical imaging and free-space optical communication. In this study, our focus was to investigate a novel imaging laser source, specifically a low-threshold random laser enhanced by TiN nanoparticles. The results demonstrate that the random laser spectrum exhibits an impressive bandwidth of 0.23 nm, accompanied by an incredibly low spatial coherence factor of merely 0.15. Due to the low spatial coherence of random laser, the speck contrast is less than 0.02 when the light passes through a scattering system. Notably, when compared to traditional lasers, the use of a random laser yields significantly superior imaging quality in both scatterless and complex scattering environments. This finding highlights the immense potential of the random laser as a narrowband and low spatial coherence laser source for robust speckle-free imaging applications, particularly in environments with intricate scattering phenomena. Furthermore, this breakthrough can be extended to various other domains, including free-space optical communication.

Cities consume a large amount of energies owing to their high population density and centralized economy, and have high concentration of various risks. Energy and transportation are key areas for carbon emission reduction in urban areas and significant components of urban lifeline engineering. Therefore, the integrated development of energy and transportation systems is crucial for the low-carbon and resilient construction of cities. This study first reviews the low-carbon and resilient development status of urban rail transit and energy systems, covering three aspects: low-carbon development of urban rail transit, resilience assessment and improvement, and security protection and risk assessment of energy storage systems. Moreover, the concept of an underground-spacesupported multi-energy-integrated urban rail transit system is proposed, elaborating the operating modes of the system in normal times and extreme conditions. Subsequently, benefits of the proposed system are analyzed from the perspectives of environment, economy,and society, and future research directions and key problems to be solved are introduced. Furthermore, the following suggestions are proposed: (1) improving the policy mechanism for the multi-energy-integrated urban rail transit system and promoting coordinated governance by multiple departments, (2) constructing a technology innovation system for the system to realize low-carbon, safe, and efficient operation of urban rail transit, and (3) promoting the development of a coordinated management system for urban power grids and rail transit to enhance urban resilience.

Although low emission hydrogen has the prospect of huge growth in the future, the cost challenge hinders the deployment and makes it weak in the global market share. Green hydrogen has the advantage of zero carbon emission and has achieved rapid development with the support of renewable energy. Limited by investment, electricity and technology, the large-scale application of green hydrogen faces challenges in the short term. Blue hydrogen comes from natural gas reforming, and its output is guaranteed. However, its production reaction requires high energy consumption and additional carbon emission treatment, resulting in insufficient sustainability. To solve the problem of high-efficiency and large-scale production of low emission hydrogen, a hydrogen co-production scheme combining photovoltaic electrolysis and natural gas reforming with CCS was proposed in this study. Electrolytic hydrogen production, natural gas autothermal reforming, CO 2 sequestration and saline purification in the cogeneration hydrogen production system are coupled by energy and materials such as electricity, O 2 , CO 2 and water. The scheme is applied in Sichuan-Chongqing region to verify the feasibility and effectiveness. The results show that the proposed hydrogen co-production scheme can achieve cost reduction of up to 16.4%, and has long-term development prospects. [Display omitted] • Identifies the development status and bottlenecks of low-emission hydrogen. • Proposes a zero carbon emission co-production scheme of green and blue hydrogen. • Verifies the feasibility and benefit of the scheme in Sichuan-Chongqing region. [ABSTRACT FROM AUTHOR]

The solidification technology of natural rubber exerts a significant impact on the properties of natural rubber. The solidification technology of alkaline protease has been highly valued by researchers at home and abroad because of its good solidification effect, excellent vulcanization performance, and low pollution. In this study, the effects of alkaline protease solidification technology and enzyme dosage on the structure and properties of natural rubber were investigated and compared with those of formic acid solidification technology. The solid‐state NMR results showed that increasing the enzyme dosage increased the molecular chain entanglements in the raw rubber. The gel content test results showed that the natural network structures (i.e. gels) increased after the addition of alkaline protease. The test results of the vulcanization characteristics showed that the addition of alkaline protease significantly shortened the positive vulcanization time. The Mw was the largest at an enzyme dosage of 0.07%. The test results for mechanical properties showed that the mechanical properties were best when the enzyme dosage was 0.07%. In addition, as the alkaline protease dosage increased, the Akron abrasion volume of natural rubber decreased, and the Akron abrasion volume was the lowest at an enzyme dosage of 0.07%. [ABSTRACT FROM AUTHOR]

Modification and improvement of aging resistance in nuclear power environment for the ethylene‐propylene‐diene (EPDM) rubber has been attracting the attention of scientists. In this article, graphite modified EPDM composites (ultrafine graphite [UG]/EPDM) were prepared, and effect of graphite with sizes of 13, 2.6, and 1.3 μm on the processability, vulcanization parameters, mechanical properties, stability of radiation aging of EPDM composites were investigated, respectively. The results showed that EPDM rubber was an irradiated crosslinked polymer. The Mooney viscosity and crosslinking density of EPDM gradually increased with increasing graphite content under the effect of physical and chemical cross‐linking of graphite. The lamellar structure of graphite particles in the rubber matrix is beneficial to improvement of the mechanical properties and aging resistance of the EPDM composites and play a reinforcing role, and the sp2 hybrid structure of graphite can trap and quench free radicals, delayed the irradiation aging of EPDM. UG/EPDM composites irradiation stability was improved with increasing graphite dispersion in EPDM matrix. Under the cumulative irradiation dose of 1000 kGy, the tensile strength of blank sample and UG‐2.6 μm−10 decreased by 51.1% and 17.7%, respectively, and the hardness increased by 8.7% and 4.9%, respectively. The energy storage modulus and the corresponding glass transition temperature (Tg) of UG/EPDM composites enhanced with graphite, while the thermal stability of the composites was improved. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage plays an important role in improving the operation efficiency and reliability of power systems with high wind energy penetration. Hydrogen to power (HtP) system is the key link of hydrogen applications. However, the single HtP equipment is limited in power output range and efficiency. Hybrid HtP system is an important scheme to realize the performance complementary. A wider power output range can enrich the application scenarios of hydrogen energy storage and provide flexible and reliable energy scheduling in larger and more complex energy systems. In this study, first, a power system including traditional units, wind power generation and hybrid HtP system is established. Second, a bi‐layer hybrid HtP system optimal configuration model considering planning and operation is constructed. Then, a bi‐layer optimal configuration method based on the improved PSO algorithm is proposed. Finally, the optimization model and its solution method are applied to IEEE RTS‐96. The discussions based on the optimization results show that the hybrid HtP system has significant contributions in optimizing the output cost of traditional units, improving the utilization of wind energy, and reducing load shedding losses. [ABSTRACT FROM AUTHOR]