Objective Magnetoreception,the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation,remains a molecularly unresolved mystery in sensory biology.The putative m...Objective Magnetoreception,the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation,remains a molecularly unresolved mystery in sensory biology.The putative magnetoreceptor(MagR,previously known as IscA1)is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism;however,the functional diversity among its crossspecies homologs remains poorly understood.Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering.Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote,non-invasive magnetic modulation represents a crucial goal in this field with significant application potential.Therefore,this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities,screen for MagR-based magnetically sensitive morphology engineering pathways,and reveal the underlying molecular mechanisms.Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli(E.coli).To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins,we utilized high-throughput automated brightfield microscopic imaging and scanning electron microscopy(SEM).Furthermore,comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays,electron paramagnetic resonance(EPR)spectroscopy,ultraviolet-visible(UV-Vis)absorption,and circular dichroism(CD)spectroscopy.Additionally,100 mT static magnetic field(SMF)exposure experiments were conducted to assess magnetically tunable phenotypes,while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device(SQUID)magnetometer.Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation.From this comprehensive screen,two distinct morphological patterns were identified:hydra(Hydra vulgaris)MagR(hyMagR)promoted uniform cell elongation and filamentation,exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF.In contrast,pigeon(Columba livia)MagR(clMagR)induced only low-frequency,extreme filamentation(sporadically exceeding 80μm)with a relatively weaker magnetic morphological response.Mechanistically,our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation.Specifically,hyMagR preferentially binds ferrous iron(Fe^(2+)),whereas clMagR favors ferric iron(Fe^(3+))and forms more stable iron-sulfur clusters.Intriguingly,although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR,its cellular magnetic response was weaker.We hypothesize that the Fe^(2+)-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species(ROS)via the Fenton reaction.Exposure to an SMF synergizes with this primed redox state,triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation.Conclusion Our findings identify the Fe^(2+)/Fe^(3+)redox state as a critical determinant of MagRmediated morphological remodeling and magnetic responsiveness.This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications,and provides a plausible framework,which potentially combines intrinsic protein magnetism with redox-state modulation,for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.展开更多
AIM:Acute hypoxia can induce transient contraction of coronary arteries,leading to myocardial ischemia and even cardiac dysfunction.However,the precise regulatory mechanisms remain unclear.In this study,we ap-plied va...AIM:Acute hypoxia can induce transient contraction of coronary arteries,leading to myocardial ischemia and even cardiac dysfunction.However,the precise regulatory mechanisms remain unclear.In this study,we ap-plied various interventions to isolated porcine coronary arteries by modulating cytoplasmic calcium concentrations mediated by calcium channels on the plasma membrane and sarcoplasmic reticulum,aiming to investigate the relationship between hypoxic contraction and intracellular calcium levelsaswell as calcium sensitization effects.METHODS:Isolated rings of the porcine left anterior descending coronary artery served as the experimental model.Based on distinct intervention tar-gets,four core experimental groups were established.The specific grouping,sample size(n)for each group,and treat-ments were as follows:(1)nitric oxide(NO)-soluble guanylyl cyclase(sGC)pathway and energy metabolism intervention groups including control(n=5),nitric oxide synthase inhibitor nitro-L-arginine(NLA,10^(-4)mol/L;n=4 to 5),soluble guanylyl cyclase(sGC)antagonist 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one(ODQ,3×10^(-5)mol/L;n=5),endothe-lium-denuded(n=5),normal glucose incubation(n=3),and glucose-free incubation(n=3)groups;(2)calcium source intervention groups including normal calcium control(n=4),calcium-free incubation with 5×10^(-3)mol/L ethylene glycol tet-raacetic acid(EGTA;n=4),L-type calcium channel antagonist nifedipine(10^(-6)mol/L;n=5 to 7),non-selective cation channel inhibitor NiCl2(5×10^(-5)mol/L;n=5 to 7),sarcoplasmic reticulum Ca^(2+)-ATPase inhibitor thapsigargin(2×10^(-6)mol/L;n=5 to 7),and inositol trisphosphate(IP3)receptor antagonist 2-aminoethoxydiphenyl borate(2-APB,10^(-4)mol/L;n=5 to 7)groups;(3)myosin light chain kinase(MLCK)pathway intervention groups including control(n=4)and MLCK-specific inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride(ML-7,10^(-5)mol/L;n=6)groups;(4)myosin light chain phosphatase(MLCP)activity and endothelium-dependence intervention groups including endothelium-intact(n=4)and mechanically endothelium-denuded(n=6)groups.All arterial rings were pre-contracted with either U46619(3×10^(-7)mol/L)or KCl(6×10^(-2)mol/L)and then subjected to 10 minutes of hypoxia(95%N2+5%CO_(2)).Changes in vascular tension were continuously monitored and recorded using a multi-channel physiological signal acquisition system.Furthermore,combined with Western blotting,the phosphorylation level of myosin light chain(MLC)and the activity of MLCP were determined;the phosphorylation levels of MLC and MLCP were also compared between en-dothelium-intact and endothelium-denuded coronary arteries under hypoxic conditions.RESULTS:(1)Hypoxic constric-tion of porcine coronary arteries is dependent on the activation of endothelium-derived nitric oxide(NO)and sGCin vascu-lar smooth muscle cells.(2)Hypoxic contraction in porcine coronary arteries is independent of extracellular Ca^(2+)influx.(3)Hypoxic contraction in porcine coronary arteries does not rely on intracellular Ca^(2+)release from the sarcoplasmic reticu-lum.(4)Hypoxic contraction in porcine coronary arteries leads to inhibition of myosin light chain phosphatase activity,suggesting increased calcium sensitization in coronary artery smooth muscle.CONCLUSION:The mechanism under-lying acute hypoxia-induced vasoconstriction exhibits distinct characteristics:it does not rely on extracellular calcium influx mediated by plasma membrane calcium channels,nor is it associated with intracellular calcium mobilization from sar-coplasmic reticulum stores.Instead,it is mediated by a significant enhancement in calcium sensitivity regulated by myo-sin light chain phosphatase,a process referred to as calcium sensitization.展开更多
Utilizing the first-principles calculation method of density functional theory,we investigate the electronic and mechanical properties of metal azides MN_(3)(M=Li,Na,Ag,Cu)and X(N_(3))_(2)(X=Cu,Hg,Pb),and explore thei...Utilizing the first-principles calculation method of density functional theory,we investigate the electronic and mechanical properties of metal azides MN_(3)(M=Li,Na,Ag,Cu)and X(N_(3))_(2)(X=Cu,Hg,Pb),and explore their correlation with impact sensitivity.The findings indicate that the impact sensitivities of the seven metal azides can be roughly ranked by considering both the band gap of the crystal and the relative atomic mass energy of the metal.Furthermore,it is suggested that the strong covalent nature of the metal-N in the upper valence band may be a significant factor contributing to the sensitivity observed in Cu(N_(3))_(2)and CuN_(3).The dominance of azide in the upper valence band while that of metal cations in lower conduction bands could explain why Hg(N_(3))_(2)and Pb(N_(3))_(2)exhibit higher sensitivity levels.Additionally,an analysis on mechanical properties reveals that the mechanical properties of metal azides will greatly affect their impact sensitivity,and the compression resistance is the most influential factor.展开更多
This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation m...This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation method(DDM)with the linear multibody system transfer matrix method(linear MSTMM).The rigid-flexible coupled multibody system dynamics model of a tracked vehicle is established using the linear MSTMM and validated through the modal test.Building upon the existing DDM-based eigenvalue sensitivity analysis method within the linear MSTMM,the DDM is embedded into it to enable programmable and efficient computation of dynamic response sensitivities for mechanical systems.The proposed approach is used to quantitatively evaluate the sensitivities of both natural vibration characteristics(e.g.,natural frequencies and mode shapes)and transient dynamic responses of the tracked vehicle with respect to system parameters,successfully identifying critical structural parameters.Compared to conventional finite difference methods,the developed methodology eliminates sensitivity to perturbation step sizes.The contributions of this work lie in establishing a unified theoretical foundation and analysis framework for guiding dynamics optimization and design of mechanical systems,and extending the applicability of the linear MSTMM to sensitivity analysis of transient dynamic responses.展开更多
In order to analyze the influences of storage aging on the safety of typical elemental explosives,the aged cyclotrimethylene trinitramine(RDX)and cyclotetramethylene tetranitramine(HMX)were prepared by isothermal agin...In order to analyze the influences of storage aging on the safety of typical elemental explosives,the aged cyclotrimethylene trinitramine(RDX)and cyclotetramethylene tetranitramine(HMX)were prepared by isothermal aging tests.The reaction thresholds of aged RDX and HMX under any ignition probability were studied by Langlie-Optimal D method.The thermal decomposition characteristics of RDX and HMX after aging were analyzed by DSC and ARC.Experimental results showed that compared with unaged RDX and HMX,on the one hand,the critical impact energy and critical friction of RDX and HMX aged for 14,28,and 56 days are significantly reduced at an explosion probability of 50%,0.01%,and 0.0001%,respectively.With the increase of aging time,the mechanical sensitivity of RDX and HMX increases obviously.On the other hand,the initial decomposition temperature of RDX and HMX after 56 days of aging decreases,the decomposition heat decreases,the activation energy increases,and the reaction difficulty increases.展开更多
Rice sheath blight is one of the serious rice diseases causing economic losses worldwide.Shenqinmycin,a broad-spectrum microbial metabolite pesticide,inhibits plant pathogens.This study investigated the sensitivity of...Rice sheath blight is one of the serious rice diseases causing economic losses worldwide.Shenqinmycin,a broad-spectrum microbial metabolite pesticide,inhibits plant pathogens.This study investigated the sensitivity of rice sheath blight pathogen to the biological pesticide by treating 45 strains isolated from three northeastern provinces with varying concentrations of Shenqinmycin.The effects on mycelial growth and sclerotial germination of the rice sheath blight pathogens were measured to determine the resistance levels.The results indicated that all tested strains were sensitive to Shenqinmycin,with EC50 values for Rhizoctonia solani ranging from 0.0487 mg·L^(-1) to 0.2348 mg·L^(-1),and a sensitivity baseline of 0.1292 mg·L^(-1).For Rhizoctonias oryzae-sativae,the EC50 values ranged from 0.0517 mg·L^(-1) to 0.1697 mg·L^(-1),with a sensitivity baseline of 0.1163 mg·L^(-1).Shenqinmycin had no effect on the sclerotial germination of either pathogen,suggesting its potential as an effective agent for controlling rice sheath blight.展开更多
The primary concern in stealth aircraft design is the very large electrical size objects.However,the computational and storage requirements of these objects present significant obstacles for current highfidelity desig...The primary concern in stealth aircraft design is the very large electrical size objects.However,the computational and storage requirements of these objects present significant obstacles for current highfidelity design methods,particularly when addressing high-dimensional complex engineering design problems.To address these challenges,we developed a surface sensitivity technique based on the multilevel fast multipole algorithm(MLFMA).An access and storage of sparse partial derivative tensor was improved to significantly enhanced the computation performance.The far-field interactions of the surface sensitivity equation were realized by differential the multipole expansion.In addition,we proposed a fast far-field multiplication method to accelerate the multiplication process.The surface mesh derivative with respect to the design variables was calculated by analytical and complex variable methods,substantially improving computational efficiency.These advancements enabled the MLFMAbased surface sensitivity method to millions meshes and large-scale gradients,extending gradientbased optimization for very large electrical size problems.Test cases have verified the effectiveness of this method in optimizing very large electrical objects in terms of both accuracy and efficiency.展开更多
The effect of hot deformation on the quench sensitivity of the 7085 alloy was studied through hardness testing and microstructure characterization.The findings indicate that hot deformation enhances the quench sensiti...The effect of hot deformation on the quench sensitivity of the 7085 alloy was studied through hardness testing and microstructure characterization.The findings indicate that hot deformation enhances the quench sensitivity of the 7085 alloy,with the hardness difference between water quenching and air cooling increasing from 5.4%(before hot deformation)to 10.4%(after hot deformation).In the undeformed samples,the Al3Zr particles within the grains exhibit better coherent with the Al matrix.During slow quenching,only theηphase is observed on Al3Zr particles and at the grain boundaries.Hot deformation leads to a mass of recrystallization and the formation of subgrains with high dislocation density.This results in an increase in the types,quantities,and sizes of heterogeneous precipitates during quenching.In the slow quenching process,high angle grain boundaries are best for the nucleation and growth of theηphase.Secondly,a substantial quantity ofηand T phases precipitate on the non-coherent Al3Zr phase within the recrystallized grains.The locations with high dislocation density subgrains(boundaries)serve as nucleation positions for theηand T phases precipitating.Additionally,the Y phase is observed to precipitate at dislocation sites within the subgrains.展开更多
Key methods developed and used in the USSR and in the Russian Federation to determine the impact and friction sensitivity of energetic materials and explosives have been discussed.Experimental methodologies and instru...Key methods developed and used in the USSR and in the Russian Federation to determine the impact and friction sensitivity of energetic materials and explosives have been discussed.Experimental methodologies and instruments that underlie the assessment of their production and handling safety have been described.Studies of a large number of compounds have revealed relationships between their sensitivity parameters and structure of individual compounds and compositions.The range of change of physical and chemical characteristics for the compounds we examined covers the entire region of their existence.Theoretical methodology and equations have been formulated to estimate the impact and friction sensitivity parameters of energetic materials and to evaluate the technological safety in use.The developed methodology is characterized by high-accuracy calculations and prediction of sensitivity parameters.展开更多
Interaction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)/ammonium perchlorate(AP) and its effect on mechanical sensitivity may result in some restrictions for the application of AP/HMX system in high energetic weapo...Interaction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)/ammonium perchlorate(AP) and its effect on mechanical sensitivity may result in some restrictions for the application of AP/HMX system in high energetic weapon system. In this work, impact sensitivity test is used to study the effects of wax coating of HMX, AP and aluminum(Al) powder on sensitivity properties of HMX/AP/Al mixtures.Thermogravimetry-differential scanning calorimetry(TG-DSC) analysis has been developed to investigate the mechanism of interaction between HMX and AP during the course of thermal decomposition of HMX/AP/AI mixtures. The results show that severe interaction effect exists between AP and HMX, which causes the impact sensitivity(H_(50)) to become smaller. The impact energy(E_(50)) of mixture can be improved under the circumstances of effective separating HMX from AP by surface coating with Wax. AP may firstly engender low-temperature decomposition under the circumstance of external heat or mechanical impact, which causes the exothermic peak of HMX forward shift about 28 C. The gaseous product releasing from thermal decomposition of HMX accelerates further decomposition of AP. For HMX/AP composite system, the interactive catalysis effect between AP and HMX can be eliminated mostly by adding a great deal of Al powder(i.e. above 30%).展开更多
The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced ...The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.展开更多
The mechanical properties of cemented paste backfill(CPB) depend heavily on its pore structural characteristics and micro-structural changes. In order to explore the variation mechanisms of macro-mechanical characteri...The mechanical properties of cemented paste backfill(CPB) depend heavily on its pore structural characteristics and micro-structural changes. In order to explore the variation mechanisms of macro-mechanical characteristics and micro-structure of CPB. CPB specimens with different mass concentrations prepared from the full tailings of Xianglushan Tungsten Ore were micro-tests. Moreover, acquired pore digital images were processed by using the pores(particles) and cracks analysis system(PCAS), and a sensitivity analysis was performed. The results show that as the mass concentration of CPB increases from 70% to 78%, the porosity, the average pore area and the number of pores drop overall, leading to a decline in the pores opening degree and enhancing the mechanical characteristics. As the mass concentration of CPB increases, the trend of fractal dimension, probability entropy and roundness is reduced, constant and increased, which can result in an enhancement of the uniformity, an unchanged directionality and more round pores. According to the definition of sensitivity, the sensitivities of various micro-parameters were calculated and can be ranked as porosity > average pore area > number of pores > roundness > fractal dimension > probability entropy.展开更多
To overcome the deficiencies addressed in the conventional PID control and improve the dynamic performance and robustness of the system, a simple design and parameters tuning approach of internal model control-PID （I...To overcome the deficiencies addressed in the conventional PID control and improve the dynamic performance and robustness of the system, a simple design and parameters tuning approach of internal model control-PID （IMC-PID） controller was proposed for the first order plus time-delay （FOPTD） process and the second order plus time-delay （SOPTD） process. By approximating the time-delay term of the process model with the first-order Taylor series, the expressions for IMC-PID controller parameters were derived, and they had only one adjustable parameter 2 which was directly related to the dynamic performance and robustness of the system. Moreover, an analytical approach of selecting 2 was given based on the maximum sensitivity Ms. Then, the robust tuning of the system could be achieved according to the value of Ms. In addition, the proposed method could be extended to the integrator plus time-delay （IPTD） process and the first order delay integrating （FODI） process. Simulation studies were carried out on various processes with time-delay, and the results show that the proposed method could provide a better dynamic performance of both the set-point tracking and disturbance rejection and robustness against parameters perturbation.展开更多
High-speed bogie frame is a key mechanical component in a train system. The reliability analysis of the bogie is necessary to the safety of high-speed train. Reliability analysis of a bogie frame was considered. The e...High-speed bogie frame is a key mechanical component in a train system. The reliability analysis of the bogie is necessary to the safety of high-speed train. Reliability analysis of a bogie frame was considered. The equivalent load method was employed to account for random repeated loads in structural reliability analysis. Degradation of material strength was regarded as a Gamma process. The probabilistic perturbation method was, then, employed for response moment computation. Example of a high-speed train bogie structure under time-variant load was employed for reliability and sensitivity analyses. Monte-Carlo simulation verifies the accuracy and efficiency of the proposed method in time-variant reliability analysis. The analysis results show that the reliability calculation considering the strength degradation and repeated load is closer to the practicality than the method of considering reliability calculation only. Its decreasing velocity is faster than the traditional reliability. The reliability sensitivity value changes over time. The analysis results provide a variation trend of reliability and sensitivity to design and usage of bogie frame.展开更多
Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is stron...Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is strongly perceived and may be a serious source of driver annoyance. Thus, many studies regarding the cavity noise mechanism and its reduction have already been conducted. In this work, a vibro-acoustic coupled analysis was conducted between a tire structure and air cavity. Using this analysis, we can more accurately simulate the tire noise performance in the region of the cavity resonance frequency. An analysis of the effects of variation of tire contour design factors was conducted, using design-of-experiments methods. Finally, a multi-objective optimization was performed using in-house codes to reduce the cavity noise level while minimizing the loss of other performances, such as diminished ride comfort and handling caused by the variations of contour. As a result of this optimization, an optimized contour shape was derived, which satisfied the multi-objective performances.展开更多
Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained...Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For comparison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.展开更多
With the fast growth of Chinese economic, more and more capital will be invested in environmental projects. How to select the environmental investment projects （alternatives） for obtaining the best environmental qua...With the fast growth of Chinese economic, more and more capital will be invested in environmental projects. How to select the environmental investment projects （alternatives） for obtaining the best environmental quality and economic benefits is an important problem for the decision makers. The purpose of this paper is to develop a decision-making model to rank a finite number of alternatives with several and sometimes conflicting criteria. A model for ranking the projects of municipal sewage treatment plants is proposed by using exports＇ information and the data of the real projects. And, the ranking result is given based on the PROMETHEE method. Furthermore, by means of the concept of the weight stability intervals （WSI）, the sensitivity of the ranking results to the size of criteria values and the change of weights value of criteria are discussed. The result shows that some criteria, such as “proportion of benefit to project cost”, will influence the ranking result of alternatives very strong while others not. The influence are not only from the value of criterion but also from the changing the weight of criterion. So, some criteria such as “proportion of benefit to project cost” are key critera for ranking the projects. Decision makers must be cautious to them.展开更多
A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications.However,quantitative prediction of the sensitivities is difficult.Here,reactive molecular dynamics simu...A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications.However,quantitative prediction of the sensitivities is difficult.Here,reactive molecular dynamics simulation models for high-speed piston impacts on explosive supercells were established.Simulations were also performed to investigate shock-induced reactions of various high-energy explosives.The fraction of reacted explosive molecules in an initial supercell changed linearly with the propagation distance of the shock-wave front.The corresponding slope could be used as a reaction rate for a specific shock-loading velocity.Reaction rates that varied with the shock-loading pressure exhibited two-stage linearities with different slopes.The two inflection points corresponded to the initial and accelerated reactions,which respectively correlated to the thresholds of shock-induced ignition and detonation.Therefore,the ignition and detonation critical pressures could be determined.The sensitivity could then be a quantitative prediction of the critical pressure.The accuracies of the quantitative shock sensitivity predictions were verified by comparing the impact and shock sensitivities of common explosives and the characteristics of anisotropic shock-induced reactions.Molecular dynamics simulations quantitatively predict and rank shock sensitivities by using only crystal structures of the explosives.Overall,this method will enable the design and safe use of explosives.展开更多
文摘Objective Magnetoreception,the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation,remains a molecularly unresolved mystery in sensory biology.The putative magnetoreceptor(MagR,previously known as IscA1)is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism;however,the functional diversity among its crossspecies homologs remains poorly understood.Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering.Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote,non-invasive magnetic modulation represents a crucial goal in this field with significant application potential.Therefore,this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities,screen for MagR-based magnetically sensitive morphology engineering pathways,and reveal the underlying molecular mechanisms.Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli(E.coli).To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins,we utilized high-throughput automated brightfield microscopic imaging and scanning electron microscopy(SEM).Furthermore,comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays,electron paramagnetic resonance(EPR)spectroscopy,ultraviolet-visible(UV-Vis)absorption,and circular dichroism(CD)spectroscopy.Additionally,100 mT static magnetic field(SMF)exposure experiments were conducted to assess magnetically tunable phenotypes,while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device(SQUID)magnetometer.Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation.From this comprehensive screen,two distinct morphological patterns were identified:hydra(Hydra vulgaris)MagR(hyMagR)promoted uniform cell elongation and filamentation,exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF.In contrast,pigeon(Columba livia)MagR(clMagR)induced only low-frequency,extreme filamentation(sporadically exceeding 80μm)with a relatively weaker magnetic morphological response.Mechanistically,our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation.Specifically,hyMagR preferentially binds ferrous iron(Fe^(2+)),whereas clMagR favors ferric iron(Fe^(3+))and forms more stable iron-sulfur clusters.Intriguingly,although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR,its cellular magnetic response was weaker.We hypothesize that the Fe^(2+)-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species(ROS)via the Fenton reaction.Exposure to an SMF synergizes with this primed redox state,triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation.Conclusion Our findings identify the Fe^(2+)/Fe^(3+)redox state as a critical determinant of MagRmediated morphological remodeling and magnetic responsiveness.This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications,and provides a plausible framework,which potentially combines intrinsic protein magnetism with redox-state modulation,for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.
基金Supported by the Zhejiang Provincial Natural Science Foundation(No.LYY22H310001)。
文摘AIM:Acute hypoxia can induce transient contraction of coronary arteries,leading to myocardial ischemia and even cardiac dysfunction.However,the precise regulatory mechanisms remain unclear.In this study,we ap-plied various interventions to isolated porcine coronary arteries by modulating cytoplasmic calcium concentrations mediated by calcium channels on the plasma membrane and sarcoplasmic reticulum,aiming to investigate the relationship between hypoxic contraction and intracellular calcium levelsaswell as calcium sensitization effects.METHODS:Isolated rings of the porcine left anterior descending coronary artery served as the experimental model.Based on distinct intervention tar-gets,four core experimental groups were established.The specific grouping,sample size(n)for each group,and treat-ments were as follows:(1)nitric oxide(NO)-soluble guanylyl cyclase(sGC)pathway and energy metabolism intervention groups including control(n=5),nitric oxide synthase inhibitor nitro-L-arginine(NLA,10^(-4)mol/L;n=4 to 5),soluble guanylyl cyclase(sGC)antagonist 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one(ODQ,3×10^(-5)mol/L;n=5),endothe-lium-denuded(n=5),normal glucose incubation(n=3),and glucose-free incubation(n=3)groups;(2)calcium source intervention groups including normal calcium control(n=4),calcium-free incubation with 5×10^(-3)mol/L ethylene glycol tet-raacetic acid(EGTA;n=4),L-type calcium channel antagonist nifedipine(10^(-6)mol/L;n=5 to 7),non-selective cation channel inhibitor NiCl2(5×10^(-5)mol/L;n=5 to 7),sarcoplasmic reticulum Ca^(2+)-ATPase inhibitor thapsigargin(2×10^(-6)mol/L;n=5 to 7),and inositol trisphosphate(IP3)receptor antagonist 2-aminoethoxydiphenyl borate(2-APB,10^(-4)mol/L;n=5 to 7)groups;(3)myosin light chain kinase(MLCK)pathway intervention groups including control(n=4)and MLCK-specific inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride(ML-7,10^(-5)mol/L;n=6)groups;(4)myosin light chain phosphatase(MLCP)activity and endothelium-dependence intervention groups including endothelium-intact(n=4)and mechanically endothelium-denuded(n=6)groups.All arterial rings were pre-contracted with either U46619(3×10^(-7)mol/L)or KCl(6×10^(-2)mol/L)and then subjected to 10 minutes of hypoxia(95%N2+5%CO_(2)).Changes in vascular tension were continuously monitored and recorded using a multi-channel physiological signal acquisition system.Furthermore,combined with Western blotting,the phosphorylation level of myosin light chain(MLC)and the activity of MLCP were determined;the phosphorylation levels of MLC and MLCP were also compared between en-dothelium-intact and endothelium-denuded coronary arteries under hypoxic conditions.RESULTS:(1)Hypoxic constric-tion of porcine coronary arteries is dependent on the activation of endothelium-derived nitric oxide(NO)and sGCin vascu-lar smooth muscle cells.(2)Hypoxic contraction in porcine coronary arteries is independent of extracellular Ca^(2+)influx.(3)Hypoxic contraction in porcine coronary arteries does not rely on intracellular Ca^(2+)release from the sarcoplasmic reticu-lum.(4)Hypoxic contraction in porcine coronary arteries leads to inhibition of myosin light chain phosphatase activity,suggesting increased calcium sensitization in coronary artery smooth muscle.CONCLUSION:The mechanism under-lying acute hypoxia-induced vasoconstriction exhibits distinct characteristics:it does not rely on extracellular calcium influx mediated by plasma membrane calcium channels,nor is it associated with intracellular calcium mobilization from sar-coplasmic reticulum stores.Instead,it is mediated by a significant enhancement in calcium sensitivity regulated by myo-sin light chain phosphatase,a process referred to as calcium sensitization.
文摘Utilizing the first-principles calculation method of density functional theory,we investigate the electronic and mechanical properties of metal azides MN_(3)(M=Li,Na,Ag,Cu)and X(N_(3))_(2)(X=Cu,Hg,Pb),and explore their correlation with impact sensitivity.The findings indicate that the impact sensitivities of the seven metal azides can be roughly ranked by considering both the band gap of the crystal and the relative atomic mass energy of the metal.Furthermore,it is suggested that the strong covalent nature of the metal-N in the upper valence band may be a significant factor contributing to the sensitivity observed in Cu(N_(3))_(2)and CuN_(3).The dominance of azide in the upper valence band while that of metal cations in lower conduction bands could explain why Hg(N_(3))_(2)and Pb(N_(3))_(2)exhibit higher sensitivity levels.Additionally,an analysis on mechanical properties reveals that the mechanical properties of metal azides will greatly affect their impact sensitivity,and the compression resistance is the most influential factor.
基金supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20241443)the Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2024ZB072)the National Natural Science Foundation of China(Grant No.92266201).
文摘This study aims to establish an integrated sensitivity analysis framework for optimization and design of the dynamic performance of mechanical systems such as tracked vehicles,by combining the direct differentiation method(DDM)with the linear multibody system transfer matrix method(linear MSTMM).The rigid-flexible coupled multibody system dynamics model of a tracked vehicle is established using the linear MSTMM and validated through the modal test.Building upon the existing DDM-based eigenvalue sensitivity analysis method within the linear MSTMM,the DDM is embedded into it to enable programmable and efficient computation of dynamic response sensitivities for mechanical systems.The proposed approach is used to quantitatively evaluate the sensitivities of both natural vibration characteristics(e.g.,natural frequencies and mode shapes)and transient dynamic responses of the tracked vehicle with respect to system parameters,successfully identifying critical structural parameters.Compared to conventional finite difference methods,the developed methodology eliminates sensitivity to perturbation step sizes.The contributions of this work lie in establishing a unified theoretical foundation and analysis framework for guiding dynamics optimization and design of mechanical systems,and extending the applicability of the linear MSTMM to sensitivity analysis of transient dynamic responses.
基金supported by the National Key Laboratory of Energetic Materials, China (Grant No. 2023-LB-036-09).
文摘In order to analyze the influences of storage aging on the safety of typical elemental explosives,the aged cyclotrimethylene trinitramine(RDX)and cyclotetramethylene tetranitramine(HMX)were prepared by isothermal aging tests.The reaction thresholds of aged RDX and HMX under any ignition probability were studied by Langlie-Optimal D method.The thermal decomposition characteristics of RDX and HMX after aging were analyzed by DSC and ARC.Experimental results showed that compared with unaged RDX and HMX,on the one hand,the critical impact energy and critical friction of RDX and HMX aged for 14,28,and 56 days are significantly reduced at an explosion probability of 50%,0.01%,and 0.0001%,respectively.With the increase of aging time,the mechanical sensitivity of RDX and HMX increases obviously.On the other hand,the initial decomposition temperature of RDX and HMX after 56 days of aging decreases,the decomposition heat decreases,the activation energy increases,and the reaction difficulty increases.
基金Supported by the Green Plant Protection Project(213010801)the Heilongjiang Provincial Key R&D Program Projects(20232X02B0502)。
文摘Rice sheath blight is one of the serious rice diseases causing economic losses worldwide.Shenqinmycin,a broad-spectrum microbial metabolite pesticide,inhibits plant pathogens.This study investigated the sensitivity of rice sheath blight pathogen to the biological pesticide by treating 45 strains isolated from three northeastern provinces with varying concentrations of Shenqinmycin.The effects on mycelial growth and sclerotial germination of the rice sheath blight pathogens were measured to determine the resistance levels.The results indicated that all tested strains were sensitive to Shenqinmycin,with EC50 values for Rhizoctonia solani ranging from 0.0487 mg·L^(-1) to 0.2348 mg·L^(-1),and a sensitivity baseline of 0.1292 mg·L^(-1).For Rhizoctonias oryzae-sativae,the EC50 values ranged from 0.0517 mg·L^(-1) to 0.1697 mg·L^(-1),with a sensitivity baseline of 0.1163 mg·L^(-1).Shenqinmycin had no effect on the sclerotial germination of either pathogen,suggesting its potential as an effective agent for controlling rice sheath blight.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFB3002800).
文摘The primary concern in stealth aircraft design is the very large electrical size objects.However,the computational and storage requirements of these objects present significant obstacles for current highfidelity design methods,particularly when addressing high-dimensional complex engineering design problems.To address these challenges,we developed a surface sensitivity technique based on the multilevel fast multipole algorithm(MLFMA).An access and storage of sparse partial derivative tensor was improved to significantly enhanced the computation performance.The far-field interactions of the surface sensitivity equation were realized by differential the multipole expansion.In addition,we proposed a fast far-field multiplication method to accelerate the multiplication process.The surface mesh derivative with respect to the design variables was calculated by analytical and complex variable methods,substantially improving computational efficiency.These advancements enabled the MLFMAbased surface sensitivity method to millions meshes and large-scale gradients,extending gradientbased optimization for very large electrical size problems.Test cases have verified the effectiveness of this method in optimizing very large electrical objects in terms of both accuracy and efficiency.
基金Project(52205421)supported by the National Natural Science Foundation of ChinaProject(AA23023028)supported by the Guangxi Science and Technology Major Project,China+2 种基金Projects(2022B0909070001,2020B010186001)supported by the Key Research and Development Projects of Guangdong Province,ChinaProject(2021B0101220006)supported by the Guangdong Key Areas Research and Development Program“Chip,Software and Computing”Major Project,ChinaProjects(2021RC2087,2022JJ30570)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘The effect of hot deformation on the quench sensitivity of the 7085 alloy was studied through hardness testing and microstructure characterization.The findings indicate that hot deformation enhances the quench sensitivity of the 7085 alloy,with the hardness difference between water quenching and air cooling increasing from 5.4%(before hot deformation)to 10.4%(after hot deformation).In the undeformed samples,the Al3Zr particles within the grains exhibit better coherent with the Al matrix.During slow quenching,only theηphase is observed on Al3Zr particles and at the grain boundaries.Hot deformation leads to a mass of recrystallization and the formation of subgrains with high dislocation density.This results in an increase in the types,quantities,and sizes of heterogeneous precipitates during quenching.In the slow quenching process,high angle grain boundaries are best for the nucleation and growth of theηphase.Secondly,a substantial quantity ofηand T phases precipitate on the non-coherent Al3Zr phase within the recrystallized grains.The locations with high dislocation density subgrains(boundaries)serve as nucleation positions for theηand T phases precipitating.Additionally,the Y phase is observed to precipitate at dislocation sites within the subgrains.
文摘Key methods developed and used in the USSR and in the Russian Federation to determine the impact and friction sensitivity of energetic materials and explosives have been discussed.Experimental methodologies and instruments that underlie the assessment of their production and handling safety have been described.Studies of a large number of compounds have revealed relationships between their sensitivity parameters and structure of individual compounds and compositions.The range of change of physical and chemical characteristics for the compounds we examined covers the entire region of their existence.Theoretical methodology and equations have been formulated to estimate the impact and friction sensitivity parameters of energetic materials and to evaluate the technological safety in use.The developed methodology is characterized by high-accuracy calculations and prediction of sensitivity parameters.
基金supported by the National Nature Science Foundation of China(Nos.11402238,11502243 and 11502245)
文摘Interaction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)/ammonium perchlorate(AP) and its effect on mechanical sensitivity may result in some restrictions for the application of AP/HMX system in high energetic weapon system. In this work, impact sensitivity test is used to study the effects of wax coating of HMX, AP and aluminum(Al) powder on sensitivity properties of HMX/AP/Al mixtures.Thermogravimetry-differential scanning calorimetry(TG-DSC) analysis has been developed to investigate the mechanism of interaction between HMX and AP during the course of thermal decomposition of HMX/AP/AI mixtures. The results show that severe interaction effect exists between AP and HMX, which causes the impact sensitivity(H_(50)) to become smaller. The impact energy(E_(50)) of mixture can be improved under the circumstances of effective separating HMX from AP by surface coating with Wax. AP may firstly engender low-temperature decomposition under the circumstance of external heat or mechanical impact, which causes the exothermic peak of HMX forward shift about 28 C. The gaseous product releasing from thermal decomposition of HMX accelerates further decomposition of AP. For HMX/AP composite system, the interactive catalysis effect between AP and HMX can be eliminated mostly by adding a great deal of Al powder(i.e. above 30%).
基金Defense Research&Development Organization(DRDO),India for financial support towards this study。
文摘The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.
基金Projects(51674188,51874229,51504182)supported by the National Natural Science Foundation of ChinaProject(2018KJXX-083)supported by Shaanxi Innovative Talents Cultivate Program-New-star Plan of Science and Technology,China
文摘The mechanical properties of cemented paste backfill(CPB) depend heavily on its pore structural characteristics and micro-structural changes. In order to explore the variation mechanisms of macro-mechanical characteristics and micro-structure of CPB. CPB specimens with different mass concentrations prepared from the full tailings of Xianglushan Tungsten Ore were micro-tests. Moreover, acquired pore digital images were processed by using the pores(particles) and cracks analysis system(PCAS), and a sensitivity analysis was performed. The results show that as the mass concentration of CPB increases from 70% to 78%, the porosity, the average pore area and the number of pores drop overall, leading to a decline in the pores opening degree and enhancing the mechanical characteristics. As the mass concentration of CPB increases, the trend of fractal dimension, probability entropy and roundness is reduced, constant and increased, which can result in an enhancement of the uniformity, an unchanged directionality and more round pores. According to the definition of sensitivity, the sensitivities of various micro-parameters were calculated and can be ranked as porosity > average pore area > number of pores > roundness > fractal dimension > probability entropy.
基金Project(2007011049) supported by the Natural Science Foundation of Shanxi Province,China
文摘To overcome the deficiencies addressed in the conventional PID control and improve the dynamic performance and robustness of the system, a simple design and parameters tuning approach of internal model control-PID （IMC-PID） controller was proposed for the first order plus time-delay （FOPTD） process and the second order plus time-delay （SOPTD） process. By approximating the time-delay term of the process model with the first-order Taylor series, the expressions for IMC-PID controller parameters were derived, and they had only one adjustable parameter 2 which was directly related to the dynamic performance and robustness of the system. Moreover, an analytical approach of selecting 2 was given based on the maximum sensitivity Ms. Then, the robust tuning of the system could be achieved according to the value of Ms. In addition, the proposed method could be extended to the integrator plus time-delay （IPTD） process and the first order delay integrating （FODI） process. Simulation studies were carried out on various processes with time-delay, and the results show that the proposed method could provide a better dynamic performance of both the set-point tracking and disturbance rejection and robustness against parameters perturbation.
基金Projects(51135003,U1234208)supported by the National Natural Science Foundation of ChinaProject(IRT0816)supported by Program for Changjiang Scholars and Innovative Research Team in University of ChinaProject(N110603001)supported by the Fundamental Research Funds for the Central Universities of China
文摘High-speed bogie frame is a key mechanical component in a train system. The reliability analysis of the bogie is necessary to the safety of high-speed train. Reliability analysis of a bogie frame was considered. The equivalent load method was employed to account for random repeated loads in structural reliability analysis. Degradation of material strength was regarded as a Gamma process. The probabilistic perturbation method was, then, employed for response moment computation. Example of a high-speed train bogie structure under time-variant load was employed for reliability and sensitivity analyses. Monte-Carlo simulation verifies the accuracy and efficiency of the proposed method in time-variant reliability analysis. The analysis results show that the reliability calculation considering the strength degradation and repeated load is closer to the practicality than the method of considering reliability calculation only. Its decreasing velocity is faster than the traditional reliability. The reliability sensitivity value changes over time. The analysis results provide a variation trend of reliability and sensitivity to design and usage of bogie frame.
文摘Cavity resonance noise of passenger car tires is generated by interacting excitation between a tire structure and the fill gas (air), and generally lies in a frequency range of 200?250 Hz. As such, this noise is strongly perceived and may be a serious source of driver annoyance. Thus, many studies regarding the cavity noise mechanism and its reduction have already been conducted. In this work, a vibro-acoustic coupled analysis was conducted between a tire structure and air cavity. Using this analysis, we can more accurately simulate the tire noise performance in the region of the cavity resonance frequency. An analysis of the effects of variation of tire contour design factors was conducted, using design-of-experiments methods. Finally, a multi-objective optimization was performed using in-house codes to reduce the cavity noise level while minimizing the loss of other performances, such as diminished ride comfort and handling caused by the variations of contour. As a result of this optimization, an optimized contour shape was derived, which satisfied the multi-objective performances.
基金The project was supported by Equipment Pre-research Key Laboratory Fund(No.6142020305)The authors would like to thank Shiyanjia Lab(www.shiyanjia.com)for the support of XPS test.
文摘Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For comparison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.
基金Shanghai Leading Academic Discipline Project (T0502)Shanghai Municipal Educational Commission Project (05EZ32).
文摘With the fast growth of Chinese economic, more and more capital will be invested in environmental projects. How to select the environmental investment projects （alternatives） for obtaining the best environmental quality and economic benefits is an important problem for the decision makers. The purpose of this paper is to develop a decision-making model to rank a finite number of alternatives with several and sometimes conflicting criteria. A model for ranking the projects of municipal sewage treatment plants is proposed by using exports＇ information and the data of the real projects. And, the ranking result is given based on the PROMETHEE method. Furthermore, by means of the concept of the weight stability intervals （WSI）, the sensitivity of the ranking results to the size of criteria values and the change of weights value of criteria are discussed. The result shows that some criteria, such as “proportion of benefit to project cost”, will influence the ranking result of alternatives very strong while others not. The influence are not only from the value of criterion but also from the changing the weight of criterion. So, some criteria such as “proportion of benefit to project cost” are key critera for ranking the projects. Decision makers must be cautious to them.
基金supported by the National Natural Science Foundation of China(Grant No.11832006).
文摘A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications.However,quantitative prediction of the sensitivities is difficult.Here,reactive molecular dynamics simulation models for high-speed piston impacts on explosive supercells were established.Simulations were also performed to investigate shock-induced reactions of various high-energy explosives.The fraction of reacted explosive molecules in an initial supercell changed linearly with the propagation distance of the shock-wave front.The corresponding slope could be used as a reaction rate for a specific shock-loading velocity.Reaction rates that varied with the shock-loading pressure exhibited two-stage linearities with different slopes.The two inflection points corresponded to the initial and accelerated reactions,which respectively correlated to the thresholds of shock-induced ignition and detonation.Therefore,the ignition and detonation critical pressures could be determined.The sensitivity could then be a quantitative prediction of the critical pressure.The accuracies of the quantitative shock sensitivity predictions were verified by comparing the impact and shock sensitivities of common explosives and the characteristics of anisotropic shock-induced reactions.Molecular dynamics simulations quantitatively predict and rank shock sensitivities by using only crystal structures of the explosives.Overall,this method will enable the design and safe use of explosives.
