铜/钢爆炸焊接复合界面的显微组织及晶粒结构演化机理

采用光滑粒子仿真、先进表征和理论分析相结合的方法,对铜/钢复合材料爆炸焊接过程中的界面瞬态行为进行深入研究,并详细阐述其显微组织演化机制。根据仿真数据重构波形完整的演化过程,并揭示各种界面特征的形成机制。多尺度EBSD分析表明,界面附近区域呈多样性的晶粒结构,其演化机制主要受塑性流动、动态再结晶和凝固形核三个过程的控制。最后,通过纳米压痕实验建立晶粒结构与力学性能之间的关系。

Experimental research on the launching system of auxiliary charge with filter cartridge structure

A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the projectile.The combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the barrel.The breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the projectile.In this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the projectile.The proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the chamber.In order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are discussed.The experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak pressure.The projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,respectively.The muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the barrel.Under the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.

Microstructure and mechanical properties of Al-Fe meshing bonding interfaces manufactured by explosive welding

In order to improve the mechanical properties of Al.Fe transition joints manufactured by explosive welding,meshing bonding interfaces were obtained by prefabricating dovetail grooves in base plates.The microstructure and mechanical properties of the meshing interfaces were systematically investigated.The microstructure observation showed that metallurgical bonding without pores was created in the form of direct bonding and melting zone bonding at the interface.Fractography on tensile specimens showed cleavage fracture on the steel side and ductile fracture on the aluminum side near the interfaces.The tensile shear test results indicated that the shear strength of the meshing interface 0°and 90°was increased by 11%and 14%,respectively,when being compared to that of the ordinary Al.Fe transition joints.The values of microhardness decreased as the distance from the interface increased.After three-point bending,cracks were observed at the bonding interface for some specimens due to the existence of brittle Fe.Al compounds.

Calculating detonation performance of explosives by VLWR thermodynamics code introduced with universal VINET equation of state

Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)thermodynamic code,this paper introduced the universal solid equation of state(EOS)VINET.In order to truly reflect the compressibility of nanocarbon under the extremely high-temperature and high-pressure environment in detonation,an SVM(support vector machine)was utilized to optimize the input parameters of carbon.The detonation performance of several explosives with different densities was calculated by the optimized universal EOS,and the results show that the thermodynamic code coupled with the universal solid EOS VINET can predict the detonation performance parameters of explosives well.To investigate the application of the thermodynamic code with the improved VINET EOS in the working capacity of explosives,the interrelationship between pressure P-particle velocity u and pressure P-volume V were computed for the detonation products of TNT and HMX-based PBX(HMX:binder:insensitive agent=95:4.3:0.7)in the CJ isentropic state.A universal curve proposed by Cooper was used to compared the computed isentropic state,where the ratio of pressure to CJ state were plotted against the ratio of velocity to CJ state.The parameters of the JWL(Jones-Wilkins-Lee)EOS for detonation products were obtained by fitting the P-V curve.The cylinder tests of TNT and HMX-based PBX were numerically simulated using the LS-DYNA,it is verified that,within a certain range,the improved algorithm has superiority in describing the working capacity of explosives.

Deformation and Spallation of Explosive Welded Steels under Gas Gun Shock Loading

We investigate deformation and spallation of explosive welded bi-steel plates under gas gun shock loading.Free surface histories are measured to obtain the Hugoniot elastic limit and spall strengths at different impact velocities.Pre-and post-shock microstructures are characterized with optical metallography,scanning electron microscopy,and electron backscatter diffraction.In addition,the Vickers hardness test is conducted.Explosive welding can result in a wavy steel/steel interface,an ultrafine grain region centered at the interface,and a neighboring high deformation region,accompanied by a hardness with the highest value at the interface.Additional shock compression induces a further increase in hardness,and shock-induced deformation occurs in the form of twinning and dislocation slip and depends on the local substructure.Spall damage nucleates and propagates along the ultrafine grain region,due to the initial cracks or weak interface bonding.Spall strengths of bimetal plates can be higher than its constituents.Plate impact offers a promising method for improving explosive welding.

Effect of hydrogen-storage pressure on the detonation characteristics of emulsion explosives sensitized by glass microballoons

In this study,hydrogen-storage glass microballoons were introduced into emulsion explosives to improve the detonation performance of the explosives.The effect of hydrogen-storage pressure on the detonation characteristics of emulsion explosives was systematically investigated.Detonation velocity experiments shows that the change of sensitizing gas and the increase of hydrogen pressure have different effects on the detonation velocity.The experimental parameters of underwater explosion increase first and then decreases with the increase of hydrogen pressure.The decrease of these parameters indicates that the strength of glass microballoons is the limiting factor to improve the detonation performance of hydrogen-storage emulsion explosives.Compared with the traditional emulsion explosives,the maximum peak pressure of shock wave of hydrogen-storage emulsion explosives increases by 10.6%at 1.0 m and 10.2%at 1.2 m,the maximum values of shock impulse increase by 5.7%at 1.0 m and 19.4%at 1.2 m.The stored hydrogen has dual effects of sensitizers and energetic additives,which can improve the energy output of emulsion explosives.

CEPC Technical Design Report

The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.

Neurological Abnormality Could be the First and Only Symptom of Familial Hemophagocytic Lymphohistiocytosis: Report of Two Families

To the Editor:Hemophagocytic lymphohistiocytosis (HLH)is a life-threatening disease which impacts many parts of the body including the digestive,circulatory,and respiratory systems.The central nervous system (CNS)can also be affected,particularly in patients with familial HLH-2 (FHL-2),responsible for approximately 20% of all FHL.FHL-2 is a result of mutations to the perforin 1 (PRF1)gene,which can occur at numerous sites on the gene.

Central Nervous System Involvement in 179 Chinese Children with Hemophagocytic Lymphohistiocytosis

Background： Central nervous system （CNS） involvement is found in many patients with hemophagocytic lymphohistiocytosis （HLH）. In this study, we mainly analyzed neurological symptoms, imaging findings, cerebrospinal fluid （CSF）, and their relationship with outcomes of HLH children. Methods： Related data of 179 Chinese pediatric patients with HLH admitted to our center from January 2010 to December 2015 were analyzed retrospectively. Diagnosis and treatment were based on the H LH-2004 protocol. Two-tailed Chi-squared test was used to compare between different groups, and Kaplan-Meier survival curves were used to analyze the overall survival （OS） of patients with HLH. Results： In the present study, 21.2% （38/179） of total patients had neurological symptoms including seizure, irritability, somnolence, and unconsciousness. There were 80 （50.0%, excluding 19 patients without imaging data） patients with cranial imaging abnormalities. There were 14.7% （17/116, excluding 63 patients who did not accept lumbar puncture） of patients with abnormal CSF results. CNS involvement is defined as abnormalities in one or more of CNS symptoms, radiological findings, and CSF. Thus, 60.3% of them had CNS involvement, As for the prognosis, the median follow-up time was 3.2 years （17 lost to follow-up）. The probable 3-year OS of children was higher without CNS involvement （86.0% ± 4.6%） than those with CNS involvement （68.9% ± 4.9%, hazard ratio [HR] = 2.286, P = 0.019）, Among them, the probable 3-year OS of children without CNS symptoms was 76.0% ± 3.8%, higher than with CNS symptoms （59.5% ± 8.1%, HR = 2.147, P ： 0.047）. The 3-year OS of children with abnormal CSF was 64.7% ± 11.6%, compared with normal CSF （85.1% ± 3.7%, HR = 0.255, P = 0.038）. Conclusions： HLH patients with CNS involvement might have worse outcomes compared with those without CNS involvement, and CNS symptoms and CSF changes are more important to access the prognosis than imaging abnormality.

Clinical Research of Pulmonary Langerhans Cell Histiocytosis in Children

Background： Pulmonary Langerhans cell histiocytosis （PLCH） is an interstitial primary pulmonary disease, characterized by Langerhans cell proliferation. It is easily misdiagnosed in children. This study aimed to characterize the clinical manifestations and features of PLCH by retrospective analysis. Meihods： A retrospective analysis was performed in 117 PLCH patients out of 338 LCH patients who were admitted in our center from November 2006 to October 2013. Variables between two groups were compared by Mann-Whitney U-test and Chi-square test. Kaplan-Meier curves were constructed to compare the survival rates and Cox regression to evaluate the effect of risk factors. Results： The median age of PLCH group was significantly lower than that ofnon-PkCH group （ 18.63 months vs. 43.4 months, P 〈 0.001 ）. All PLCH children had other organ involvement and only 11 cases （9.4%） had respiratory symptoms. The most common radiologic finding was cystic lesions （29 cases, 24.8%）. Pulmonary thnction abnormalities were dominated by obstructive ventilatory dysfunction （63 cases, 82.9%）. The 5-year overall survival （OS） of PECH children was 93.6% ± 2.3% and the event-free survival （EFS） was 55.7% ± 5.2%. Among the 38 cases with progressed or relapsed disease, five cases （13.2%） were due to progression or recurrence of lung damage. The 5-year OS of PECH children with ＂risk organ＂ involvement was significantly lower than those without ＂risk organ＂ involvement （86.0% ± 4.9% vs. 100%,X^2 = 8.793, P= 0.003）. The difference of EFS between two groups was also significant （43.7% ± 7.7% vs. 66.3% ± 6.5%,X^2 = 5.399, P = 0.020）. The ＂＇risk organ＂ involvement had a significant impact on survival （hazard ratio = 1.9, P = 0.039）. Conclusions： PLCH mainly occurs in young children, and only a small percentage of patients have respiratory symptoms. They generally have other organ involvement. Most of PLCH children have a good prognosis and most lung lesions could have improved or stabilized. Management of＂risk organ＂ involvement is the key point to improving EFS.

Associations between PRF1 Ala91 Val polymorphism and risk of hemophagocytic lymphohistiocytosis: a meta-analysis based on 1366 subjects

Background Perforin(PRF1)gene mutation can cause the onset of hemophagocytic lymphohistiocytosis(HLH).It has reported that PRFl Ala91 Val polymorphism was related with HLH risk.In the meta-analysis,we aim to evaluate the association between PRF1 Ala91 Val polymorphism and HLH risk.Methods We accomplished a meta-analysis of six published case-control studies including 391 patients with HLH and 975 controls.We evaluated the quality of each study through Newcastle-Ottawa Scale(NOS).Data analysis was performed with Stata software.Results In general,all studies were of high quality(NOS score higher than 7).There were statistically significant between the PRFl Ala91 Val polymorphism and HLH risk though the pooled analysis[for Ala/Val vs.Ala/Ala:pooled odds ratio(OR)=3.22,95%confidence interval(Cl)1.08-9.56,P=0.035,random model;for Ala/Val+Val/Val vs.Ala/Ala:pooled OR=2.96,95%Cl 1.14-7.69,P=0.025,random model].Furthermore,sensitivity analysis also revealed a relationship between PRFl Ala91Val polymorphism and HLH risk(for Ala/Val vs.Ala/Ala:pooled OR=5.236,95%Cl 2.72-10.08,P<0.000,/2=12.1%,^heterogeneity=0-332;for Ala/Val+Val/Val vs.Ala/Ala,pooled OR=4.856,95%Cl 2.66-8.85,P<0.000,/2=5.9%,Pheterogeneity=0.373).Funnel plot and Egger’s test did not indicate obvious published bias(P=0.841 for Ala/Val vs.Ala/Ala;?=0.284 for Ala/Val+Val/Val vs.Ala/Ala).Conclusion This meta-analysis indicated that PRFl Ala91 Val polymorphism affects the factor for developing HLH and future studies of PRFl Ala91 Val on the onset of HLH will be guaranteed.