With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has b...With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has become more critical.Existing design guidelines for protective walls(e.g.,UFC 3-340-02)primarily address mid-and far-field explosions,providing limited insights into near-field effects.Considering the effect of slight slopes(<40°)on reducing maximum reflected overpressure is deemed negligible.This study investigated the effectiveness of a reinforced concrete(RC)modular protection system(MPS)incorpo rating a diagonally tapered wall in attenuating re flected overpressures from closein detonations.Full-scale field experiments using a 51.3 kg TNT charge,representing the explosion energy of a typical hydrogen vessel rupture,demonstrated that a wall with a 7°slope significantly outperformed a vertical wall of equivalent concrete volume in terms of blast resistance.Observed structural responses included cracking,horizontal shear failure,and overturning.Complementary simulations using a validated computational fluid dynamics(CFD)model showed that the tapered wall reduced peak overpressure by 30%-40%compared to an equivalent vertical wall.This result highlights the potential of minor geometric modifications to enhance blast resilience.The tapered design effectively redirects incident blast waves,reducing localized damage while also conserving material,thus preserving modular benefits such as ease of transport and reusability.These findings suggest that diagonally tapered RC-based MPSs can offer a practical and resilient solution for industrial and military applications subject to near-field or sequential blast threats.展开更多
A philosophy for the design of novel,lightweight,multi-layered armor,referred to as Composite Armor Philosophy(CAP),which can adapt to the passive protection of light-,medium-,and heavy-armored vehicles,is presented i...A philosophy for the design of novel,lightweight,multi-layered armor,referred to as Composite Armor Philosophy(CAP),which can adapt to the passive protection of light-,medium-,and heavy-armored vehicles,is presented in this study.CAP can serve as a guiding principle to assist designers in comprehending the distinct roles fulfilled by each component.The CAP proposal comprises four functional layers,organized in a suggested hierarchy of materials.Particularly notable is the inclusion of a ceramic-composite principle,representing an advanced and innovative solution in the field of armor design.This paper showcases real-world defense industry applications,offering case studies that demonstrate the effectiveness of this advanced approach.CAP represents a significant milestone in the history of passive protection,marking an evolutionary leap in the field.This philosophical approach provides designers with a powerful toolset with which to enhance the protection capabilities of military vehicles,making them more resilient and better equipped to meet the challenges of modern warfare.展开更多
Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this stud...Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.展开更多
Background Cotton charcoal rot disease,caused by Macrophomina phaseolina,is a major threat to cotton production in Israel and globally,leading to severe yield loss due to post-flowering plant collapse.Current manageme...Background Cotton charcoal rot disease,caused by Macrophomina phaseolina,is a major threat to cotton production in Israel and globally,leading to severe yield loss due to post-flowering plant collapse.Current management relies heavily on chemical fungicides.However,rising environmental concerns and fungicide resistance underscore the need for sustainable alternatives.This study evaluated novel clay-based formulations for the controlled release of azoxystrobin(AS).The approach aims to protect cotton during the sensitive early growth stages when pathogen penetration and colonization occur.Two types of clay carriers—bentonite(montmorillonite)and sepiolite—were tested for their ability to deliver AS effectively.Results While seedlings grown in the greenhouse showed minimal visible symptoms at the disease latent stage,quantitative real-time PCR analysis indicated that both formulations effectively suppressed root infection,reducing M.phaseolina DNA levels by 81%.In a full-season open-enclosure trial,bentonite-AS treatment exhibited reduced efficacy,possibly due to phytotoxicity at the tested concentration.In contrast,the sepiolite-AS treatment increased flower bud number by 87%and reduced pathogen infection by up to 92%at 68 days post-sowing,although these effects were not statistically significant due to high variability.At harvest,sepiolite-AS and bentonite alone increased shoot dry weight per plant by 129%and 128%,respectively,and reduced pathogen DNA levels by 63%and 69%,respectively.Conclusion Overall,although environmental variability led to statistical insignificance,the findings support the clay-AS approach,especially sepiolite,as an effective means to prevent early infection and reduce late-season disease outbreaks.This formulation holds promise for seed coating or sowing strip applications,offering a practical,eco-friendly approach that can be integrated with biological control to reduce chemical inputs across diverse cultivation systems.展开更多
Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrate...Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrates.In these coatings,a reactive emulsifier containing phosphate groups can be integrated into the molecular chain during polymerization,which enhances the coating's compactness and corrosion resistance.This work focuses on the synthesis of styrene-butyl acrylate(St-BA)latex and methyl methacrylate-butyl acrylate(MMA-BA)latex using the reactive phosphate emulsifier ANPEO_(10)-P_(1)through seed emulsion polymerization,achieving a conversion rate of approximately 99%and a solid content close to 50%.The resulting coatings from St-BA and MMA-BA latexes demonstrated long-term corrosion protection for carbon steel and aluminum alloy due to in-situ phosphatization,effectively preventing flash rust.Notably,the MMA-BA coating exhibited remarkable durability,enduring immersion for up to 1224 h(51 d)on Q 235 carbon steel before reaching the failure threshold(|Z|_(0.01 Hz)≤10^(6)Ω·cm^(2))on Q 235 carbon steel.On 5052 aluminum alloy,the St-BA coating maintained|Z|_(0.01 Hz)>10^(8)Ω·cm^(2)for 480 h(20 d).Furthermore,the corrosion resistance of St-BA and MMA BA coatings on Q 235 steel sheet and 5052 aluminum alloy surpassed that of commercially available MMA-BA and St BA coatings after immersion in a 3.5 wt%NaCl aqueous solution.This work also delves into the anticorrosion mechanism of MMA-BA and St-BA coatings.展开更多
The use of non-power frequency components for protection measurements in an area that has received relatively little attention. Although work on the use of switched stack tuners has been reported for fault detection, ...The use of non-power frequency components for protection measurements in an area that has received relatively little attention. Although work on the use of switched stack tuners has been reported for fault detection, the sensitivity of switched arrangements is limited by scnsitivity of directional detectors for switching purposes. This paper presents an alternative non-switching scheme which is relatively simple.A simplified typical 400kV system with the line trap, stack tuner, coupling capacitor and bus capacitance to earth is considered. Fault studies by using the EMTP have been carried out, frequency-dependent pararnctcrs are used for the line representation. Arcing faults have also bccn investigated and the results show a great promise of the scheme.展开更多
With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to ...With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.展开更多
In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’d...In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.展开更多
Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane ex...Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.展开更多
Recent researches focused on developing robust blast load mitigation systems due to the threats of terrorist attacks.One of the main embraced strategies is the structural systems that use mitigation techniques.They ar...Recent researches focused on developing robust blast load mitigation systems due to the threats of terrorist attacks.One of the main embraced strategies is the structural systems that use mitigation techniques.They are developed from a combination of structural elements and described herein as conventional systems.Among the promising techniques is that redirect the waves propagation through hollow tubes.The blast wave propagation through tubes provides an efficient system since it combines many blast wave phenomena,such as reflection,diffraction,and interaction.In this research,a novel blast load mitigation system,employed as a protection fence,is developed using a technique similar to the technique of the bent tube in manipulating the shock-wave.The relative performance of the novel system to the conventional system is evaluated based on mitigation percent criteria.Performances of both systems are calculated through numerical simulation.The proposed novel system proved to satisfy high performance in mitigating the generated blast waves from charges weight up to 500 kg TNT at relatively small standoff distances(5 m and 8 m).It mitigates at least 94%of the blast waves,which means that only 6%of that blast impulse is considered as the applied load on the targeted structure.展开更多
Topical Issues for the Future of Radiation Protection Kevin Nelson1, Renate Czarwinski2, Charles Wilson3, Bernard LeGuen4, Jing Chen5, Hildegarde Annie Vandenhove6, Shengli Niu7, Thierry Schneider8, John Damilakis9,10...Topical Issues for the Future of Radiation Protection Kevin Nelson1, Renate Czarwinski2, Charles Wilson3, Bernard LeGuen4, Jing Chen5, Hildegarde Annie Vandenhove6, Shengli Niu7, Thierry Schneider8, John Damilakis9,10 and Peter Alfred Bryant11,12(1.Mayo Clinic, Scottsdale, AZ 85259.展开更多
Evaluating Adherence to Safety Standards for Physical Space Design, Equipment, and Patient and Staff Protection in Magnetic Resonance Imaging Centers:A Descriptive Cross-sectional Study Amirreza Sadeghinasab1, Jafar F...Evaluating Adherence to Safety Standards for Physical Space Design, Equipment, and Patient and Staff Protection in Magnetic Resonance Imaging Centers:A Descriptive Cross-sectional Study Amirreza Sadeghinasab1, Jafar Fatahiasl2, Mahmoud Mohammadi-Sadr1, Masoud Heydari Kahkesh3, and Marziyeh Tahmasbi2(1.Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran;2.Department of Radiologic Technology, School of Allied Medical Sciences, Ahvaz, Jundishapur University of Medical Sciences, Ahvaz, Iran;3.Department of Radiology and Radiotherapy, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran)Abstract:Magnetic resonance imaging(MRI) has revolutionized disease diagnosis and treatment.However, the technology poses safety risks, such as exposure to magnetic fields, RF pulses, and cryogens, necessitating strict adherence to safety protocols to protect patients and healthcare workers.展开更多
Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon ...Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.展开更多
Aims and Scope Journal of Northeast Agricultural University(English Edition)is a comprehensive academic journal on agricultural sciences sponsored by Northeast Agricultural University and distributed worldwide.It is a...Aims and Scope Journal of Northeast Agricultural University(English Edition)is a comprehensive academic journal on agricultural sciences sponsored by Northeast Agricultural University and distributed worldwide.It is a peer reviewed journal published quarterly and mainly publishes review and research articles that reflect the latest achievements on crop science,horticulture,plant protection,resource and environment,animal science,veterinary medicine,agricultural engineering and technology,agricultural water conservancy,life science,biotechnology and food science.展开更多
With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics s...With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics susceptible to fixed boundaries,which is not conducive to practical applications.Inspired by the motion characteristics of yarn structures,this study investigates a hybrid 3D woven fabric structure that incorporates interlayer warp yarns and normal yarns.Bending stiffness tests,yarn pull-out tests,and ballistic tests are conducted and compared with single-binding yarn structures.Utilizing a validated meso-finite element model,the dynamic deformation and energy absorption mechanisms of the hybrid configuration under impact are elucidated.The results demonstrate that synergistic interactions among various binding yarn structures maintain fabric stability in the absence of boundaries.Normal yarns inhibit horizontal slippage of warp yarns,while multi-layer warp yarns enhance resistance to weft yarn pull-out,thereby facilitating greater yarn participation in direct energy absorption.The hybrid structure exhibited the highest specific energy absorption(SEA)across different boundary conditions,with an average SEA increase of approximately 27%.These insights will facilitate the design of novel hybrid-structured 3D woven fabrics and inform the customization of lightweight protective materials.展开更多
In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal...In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.展开更多
The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound st...The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound structures were used as barriers to weaken the blast loads.A comprehensive experiment using a high-speed camera and image processing techniques,side witness plates,and bottom witness plates was presented.Using the experimental fragment velocities,fragment piercing patterns,and damage characteristics,the reaction degree of the explosive impeded by different multi-layered compound structures could be precisely differentiated.Reaction parameters of the explosive obstructed by compound structures were obtained by theoretical analysis and numerical simulations.Unlike the common method in which the explosive reaction degree is only distinguished based on the initial pressure amplitude transmitted into the explosive,a following shock wave reflected from the side steel casing was also considered.Different detonation growth paths in the explosive formed.Therefore,all these shock wave propagation characteristics must be considered to analyze the explosive response impeded by compound structures.展开更多
An EMU train with detailed cabin structural is established based on the finite element method.The secondary impact between train driver and control desk is fully analysed and two measures are proposed to reduce the dr...An EMU train with detailed cabin structural is established based on the finite element method.The secondary impact between train driver and control desk is fully analysed and two measures are proposed to reduce the driver injury severity,such as the multi-objective optimization of the driver seat position and equipping the train with three-point seat belt.Simulation results indicate that the driver seat position has a significant effect on the driver injury severity during a secondary impact.According to the multi-objective optimization,some Pareto solutions are suggested to design the driver seat position.Besides that,it is also indicated although the chest and leg are well protected when the driver wears a two-point seat belt,it increases the head injure during a secondary impact.On the other hand,the three-point seat belt can supply the train driver with an overall protection against the secondary impact.The injury criteria(HIC,VC,TI)of the driver with the three-point seat belt is significantly lower than those of the driver without seat belt.Moreover,according to the simulation analysis,the limited load of the three-point seat belt is suggested about 1.5 kN.展开更多
With increasing ballistic threat levels,there is ever more demand on developing ceramic armor designs with improved performance.This paper presents finite element simulations that investigate the performance of silico...With increasing ballistic threat levels,there is ever more demand on developing ceramic armor designs with improved performance.This paper presents finite element simulations that investigate the performance of silicon carbide ceramic with steel 4340 backing material and titanium alloy,graphite as buffer layers when subjected to normal and oblique impacts by a tungsten alloy long rod projectile(LRP).Depth of penetration from experimental measurements is compared with simulations to confirm the validity of constitutive,failure model parameters.Titanium alloy cover plate and graphite interface weak layer laterally spread the impact shock away from the SiC tile and reduces the amplification of the stress accumulation at the front surface of the SiC tile.The dwelling time increases before it penetrates into ceramic armor.Further,using AUTODYN®numerical simulations detailed parametric study is carried out to identify the minimum areal density armor for a given ballistic limit velocity.The equivalent protection factor for the bi-layer armor is a simple function of the cosine of the angle of impact.展开更多
A novel copyright protection scheme for digital content is presented, which is a private watermarking scheme based on the watermark embedding in the DCT domain and watermark extraction Using independent component anal...A novel copyright protection scheme for digital content is presented, which is a private watermarking scheme based on the watermark embedding in the DCT domain and watermark extraction Using independent component analysis （ICA）. The system includes the key for watermark extraction and the host image. The algorithm splits the original image into blocks and classifies these blocks based on visual masking, that is, noise visibility function （NVF）. Watermark components with different strength are inserted into chosen direct current components of DCT coefficients according to the classifier. The watermark extraction is based on the characteristic of the statistic independence of the host image, watermark and key. Principle component analysis （PCA） whitening process and FastICA techniques are introduced to ensure a blind watermark extraction without requiring the original image. Experirnental results show the proposed technique is robust under attacks such as image filtering and adding noise, cropping and resizing. In addition, the proposed private watermarking system can be improved to the application of the DTV content protection system.展开更多
基金supported by the Dong-A University of the Republic of Korea research fund。
文摘With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has become more critical.Existing design guidelines for protective walls(e.g.,UFC 3-340-02)primarily address mid-and far-field explosions,providing limited insights into near-field effects.Considering the effect of slight slopes(<40°)on reducing maximum reflected overpressure is deemed negligible.This study investigated the effectiveness of a reinforced concrete(RC)modular protection system(MPS)incorpo rating a diagonally tapered wall in attenuating re flected overpressures from closein detonations.Full-scale field experiments using a 51.3 kg TNT charge,representing the explosion energy of a typical hydrogen vessel rupture,demonstrated that a wall with a 7°slope significantly outperformed a vertical wall of equivalent concrete volume in terms of blast resistance.Observed structural responses included cracking,horizontal shear failure,and overturning.Complementary simulations using a validated computational fluid dynamics(CFD)model showed that the tapered wall reduced peak overpressure by 30%-40%compared to an equivalent vertical wall.This result highlights the potential of minor geometric modifications to enhance blast resilience.The tapered design effectively redirects incident blast waves,reducing localized damage while also conserving material,thus preserving modular benefits such as ease of transport and reusability.These findings suggest that diagonally tapered RC-based MPSs can offer a practical and resilient solution for industrial and military applications subject to near-field or sequential blast threats.
基金co-financed by the European Regional Development Fund of the European UnionGreek national funds through the Operational Program Competitiveness,Entrepreneurship and Innovation,under the call RESEARCH-CREATE-INNOVATE(project code:T1EDK-04429)。
文摘A philosophy for the design of novel,lightweight,multi-layered armor,referred to as Composite Armor Philosophy(CAP),which can adapt to the passive protection of light-,medium-,and heavy-armored vehicles,is presented in this study.CAP can serve as a guiding principle to assist designers in comprehending the distinct roles fulfilled by each component.The CAP proposal comprises four functional layers,organized in a suggested hierarchy of materials.Particularly notable is the inclusion of a ceramic-composite principle,representing an advanced and innovative solution in the field of armor design.This paper showcases real-world defense industry applications,offering case studies that demonstrate the effectiveness of this advanced approach.CAP represents a significant milestone in the history of passive protection,marking an evolutionary leap in the field.This philosophical approach provides designers with a powerful toolset with which to enhance the protection capabilities of military vehicles,making them more resilient and better equipped to meet the challenges of modern warfare.
基金financial support from the National Key Research and Development Program(Grant No.2024YFA1209801)the National Natural Science Foundation of China(Grant Nos.12302140,12325204)+4 种基金the China Postdoctoral Science Foundation(Grant No.2023M732794)the Fundamental Research Funds for the Central Universities of China(Grant No.sxzy012023213)the Scientific Research Program of Shaanxi Province(Grant No.2023JC-XJ-02)the Young Talent Support Program of Xi'an Science and Technology Association(Grant No.959202413069)Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GZB20230575)。
文摘Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.
基金supported by a one-year research grant (2023) from ICA Israel (Jewish Colonization Association)a two-year grant (2023–2024) from Migal–Galilee Research Institute (Israel)
文摘Background Cotton charcoal rot disease,caused by Macrophomina phaseolina,is a major threat to cotton production in Israel and globally,leading to severe yield loss due to post-flowering plant collapse.Current management relies heavily on chemical fungicides.However,rising environmental concerns and fungicide resistance underscore the need for sustainable alternatives.This study evaluated novel clay-based formulations for the controlled release of azoxystrobin(AS).The approach aims to protect cotton during the sensitive early growth stages when pathogen penetration and colonization occur.Two types of clay carriers—bentonite(montmorillonite)and sepiolite—were tested for their ability to deliver AS effectively.Results While seedlings grown in the greenhouse showed minimal visible symptoms at the disease latent stage,quantitative real-time PCR analysis indicated that both formulations effectively suppressed root infection,reducing M.phaseolina DNA levels by 81%.In a full-season open-enclosure trial,bentonite-AS treatment exhibited reduced efficacy,possibly due to phytotoxicity at the tested concentration.In contrast,the sepiolite-AS treatment increased flower bud number by 87%and reduced pathogen infection by up to 92%at 68 days post-sowing,although these effects were not statistically significant due to high variability.At harvest,sepiolite-AS and bentonite alone increased shoot dry weight per plant by 129%and 128%,respectively,and reduced pathogen DNA levels by 63%and 69%,respectively.Conclusion Overall,although environmental variability led to statistical insignificance,the findings support the clay-AS approach,especially sepiolite,as an effective means to prevent early infection and reduce late-season disease outbreaks.This formulation holds promise for seed coating or sowing strip applications,offering a practical,eco-friendly approach that can be integrated with biological control to reduce chemical inputs across diverse cultivation systems.
基金Project(52373065)supported by the National Natural Science Foundation of ChinaProject(2220004002898)supported by the Zhuhai Industry University Research Cooperation and Basic and Applied Research Projects,China。
文摘Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrates.In these coatings,a reactive emulsifier containing phosphate groups can be integrated into the molecular chain during polymerization,which enhances the coating's compactness and corrosion resistance.This work focuses on the synthesis of styrene-butyl acrylate(St-BA)latex and methyl methacrylate-butyl acrylate(MMA-BA)latex using the reactive phosphate emulsifier ANPEO_(10)-P_(1)through seed emulsion polymerization,achieving a conversion rate of approximately 99%and a solid content close to 50%.The resulting coatings from St-BA and MMA-BA latexes demonstrated long-term corrosion protection for carbon steel and aluminum alloy due to in-situ phosphatization,effectively preventing flash rust.Notably,the MMA-BA coating exhibited remarkable durability,enduring immersion for up to 1224 h(51 d)on Q 235 carbon steel before reaching the failure threshold(|Z|_(0.01 Hz)≤10^(6)Ω·cm^(2))on Q 235 carbon steel.On 5052 aluminum alloy,the St-BA coating maintained|Z|_(0.01 Hz)>10^(8)Ω·cm^(2)for 480 h(20 d).Furthermore,the corrosion resistance of St-BA and MMA BA coatings on Q 235 steel sheet and 5052 aluminum alloy surpassed that of commercially available MMA-BA and St BA coatings after immersion in a 3.5 wt%NaCl aqueous solution.This work also delves into the anticorrosion mechanism of MMA-BA and St-BA coatings.
文摘The use of non-power frequency components for protection measurements in an area that has received relatively little attention. Although work on the use of switched stack tuners has been reported for fault detection, the sensitivity of switched arrangements is limited by scnsitivity of directional detectors for switching purposes. This paper presents an alternative non-switching scheme which is relatively simple.A simplified typical 400kV system with the line trap, stack tuner, coupling capacitor and bus capacitance to earth is considered. Fault studies by using the EMTP have been carried out, frequency-dependent pararnctcrs are used for the line representation. Arcing faults have also bccn investigated and the results show a great promise of the scheme.
文摘With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.
文摘In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.
基金supported by the National Natural Science Foundation of China(Grant No.52274177)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202401501)+1 种基金Chongqing Graduate Student Research Innovation Program(Grant No.CYS240800)The Science and Technology Innovation Project for Graduate Students of Chongqing University of Science and Technology(Grant No.YKJCX2420702).
文摘Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.
文摘Recent researches focused on developing robust blast load mitigation systems due to the threats of terrorist attacks.One of the main embraced strategies is the structural systems that use mitigation techniques.They are developed from a combination of structural elements and described herein as conventional systems.Among the promising techniques is that redirect the waves propagation through hollow tubes.The blast wave propagation through tubes provides an efficient system since it combines many blast wave phenomena,such as reflection,diffraction,and interaction.In this research,a novel blast load mitigation system,employed as a protection fence,is developed using a technique similar to the technique of the bent tube in manipulating the shock-wave.The relative performance of the novel system to the conventional system is evaluated based on mitigation percent criteria.Performances of both systems are calculated through numerical simulation.The proposed novel system proved to satisfy high performance in mitigating the generated blast waves from charges weight up to 500 kg TNT at relatively small standoff distances(5 m and 8 m).It mitigates at least 94%of the blast waves,which means that only 6%of that blast impulse is considered as the applied load on the targeted structure.
文摘Topical Issues for the Future of Radiation Protection Kevin Nelson1, Renate Czarwinski2, Charles Wilson3, Bernard LeGuen4, Jing Chen5, Hildegarde Annie Vandenhove6, Shengli Niu7, Thierry Schneider8, John Damilakis9,10 and Peter Alfred Bryant11,12(1.Mayo Clinic, Scottsdale, AZ 85259.
文摘Evaluating Adherence to Safety Standards for Physical Space Design, Equipment, and Patient and Staff Protection in Magnetic Resonance Imaging Centers:A Descriptive Cross-sectional Study Amirreza Sadeghinasab1, Jafar Fatahiasl2, Mahmoud Mohammadi-Sadr1, Masoud Heydari Kahkesh3, and Marziyeh Tahmasbi2(1.Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran;2.Department of Radiologic Technology, School of Allied Medical Sciences, Ahvaz, Jundishapur University of Medical Sciences, Ahvaz, Iran;3.Department of Radiology and Radiotherapy, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran)Abstract:Magnetic resonance imaging(MRI) has revolutionized disease diagnosis and treatment.However, the technology poses safety risks, such as exposure to magnetic fields, RF pulses, and cryogens, necessitating strict adherence to safety protocols to protect patients and healthcare workers.
文摘Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.
文摘Aims and Scope Journal of Northeast Agricultural University(English Edition)is a comprehensive academic journal on agricultural sciences sponsored by Northeast Agricultural University and distributed worldwide.It is a peer reviewed journal published quarterly and mainly publishes review and research articles that reflect the latest achievements on crop science,horticulture,plant protection,resource and environment,animal science,veterinary medicine,agricultural engineering and technology,agricultural water conservancy,life science,biotechnology and food science.
基金supports from National Key R&D Program for Young Scientists of China(No.2022YFC3080900)the opening project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ25-25M).
文摘With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics susceptible to fixed boundaries,which is not conducive to practical applications.Inspired by the motion characteristics of yarn structures,this study investigates a hybrid 3D woven fabric structure that incorporates interlayer warp yarns and normal yarns.Bending stiffness tests,yarn pull-out tests,and ballistic tests are conducted and compared with single-binding yarn structures.Utilizing a validated meso-finite element model,the dynamic deformation and energy absorption mechanisms of the hybrid configuration under impact are elucidated.The results demonstrate that synergistic interactions among various binding yarn structures maintain fabric stability in the absence of boundaries.Normal yarns inhibit horizontal slippage of warp yarns,while multi-layer warp yarns enhance resistance to weft yarn pull-out,thereby facilitating greater yarn participation in direct energy absorption.The hybrid structure exhibited the highest specific energy absorption(SEA)across different boundary conditions,with an average SEA increase of approximately 27%.These insights will facilitate the design of novel hybrid-structured 3D woven fabrics and inform the customization of lightweight protective materials.
基金Project(51076062) supported by the National Natural Science Foundation of China
文摘In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.
基金The authors are very grateful for the support received from the National Natural Science Foundation of China(No.11872121).
文摘The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound structures were used as barriers to weaken the blast loads.A comprehensive experiment using a high-speed camera and image processing techniques,side witness plates,and bottom witness plates was presented.Using the experimental fragment velocities,fragment piercing patterns,and damage characteristics,the reaction degree of the explosive impeded by different multi-layered compound structures could be precisely differentiated.Reaction parameters of the explosive obstructed by compound structures were obtained by theoretical analysis and numerical simulations.Unlike the common method in which the explosive reaction degree is only distinguished based on the initial pressure amplitude transmitted into the explosive,a following shock wave reflected from the side steel casing was also considered.Different detonation growth paths in the explosive formed.Therefore,all these shock wave propagation characteristics must be considered to analyze the explosive response impeded by compound structures.
基金Project(51805374) supported by the National Natural Science Foundation of ChinaProject(22120180531) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(16PJ1409500) supported by the Shanghai Pujiang Program,China
文摘An EMU train with detailed cabin structural is established based on the finite element method.The secondary impact between train driver and control desk is fully analysed and two measures are proposed to reduce the driver injury severity,such as the multi-objective optimization of the driver seat position and equipping the train with three-point seat belt.Simulation results indicate that the driver seat position has a significant effect on the driver injury severity during a secondary impact.According to the multi-objective optimization,some Pareto solutions are suggested to design the driver seat position.Besides that,it is also indicated although the chest and leg are well protected when the driver wears a two-point seat belt,it increases the head injure during a secondary impact.On the other hand,the three-point seat belt can supply the train driver with an overall protection against the secondary impact.The injury criteria(HIC,VC,TI)of the driver with the three-point seat belt is significantly lower than those of the driver without seat belt.Moreover,according to the simulation analysis,the limited load of the three-point seat belt is suggested about 1.5 kN.
基金Authors thanks Temasek Laboratories@Nanyang Technological University(TL@NTU)for the financial support through the project number TL9013103084-02.
文摘With increasing ballistic threat levels,there is ever more demand on developing ceramic armor designs with improved performance.This paper presents finite element simulations that investigate the performance of silicon carbide ceramic with steel 4340 backing material and titanium alloy,graphite as buffer layers when subjected to normal and oblique impacts by a tungsten alloy long rod projectile(LRP).Depth of penetration from experimental measurements is compared with simulations to confirm the validity of constitutive,failure model parameters.Titanium alloy cover plate and graphite interface weak layer laterally spread the impact shock away from the SiC tile and reduces the amplification of the stress accumulation at the front surface of the SiC tile.The dwelling time increases before it penetrates into ceramic armor.Further,using AUTODYN®numerical simulations detailed parametric study is carried out to identify the minimum areal density armor for a given ballistic limit velocity.The equivalent protection factor for the bi-layer armor is a simple function of the cosine of the angle of impact.
基金This project was supported by the Digital TV Special Foundation of National Development and Reform Commission ofChina (040313) Home Coming Scholars Science Activity Foundation of Ministry of Personnel (20041231) the Graduate In-novation Foundation of Xidian University (innovaion 0509)
文摘A novel copyright protection scheme for digital content is presented, which is a private watermarking scheme based on the watermark embedding in the DCT domain and watermark extraction Using independent component analysis （ICA）. The system includes the key for watermark extraction and the host image. The algorithm splits the original image into blocks and classifies these blocks based on visual masking, that is, noise visibility function （NVF）. Watermark components with different strength are inserted into chosen direct current components of DCT coefficients according to the classifier. The watermark extraction is based on the characteristic of the statistic independence of the host image, watermark and key. Principle component analysis （PCA） whitening process and FastICA techniques are introduced to ensure a blind watermark extraction without requiring the original image. Experirnental results show the proposed technique is robust under attacks such as image filtering and adding noise, cropping and resizing. In addition, the proposed private watermarking system can be improved to the application of the DTV content protection system.
