Formability limits and process window based on fracture analysis of 5A02-O aluminium alloy in splitting spinning

Splitting spinning or rotary flow splitting is an advanced forming process for manufacturing axisymmetric integrated parts with bifurcated features and unique characteristics of high-performance and low-weight. During the process, under the kinematic effects of mandrel rotational movement and roller radial feed, plastic deformation occurs accompanied usually by undesirable fracture, which reduces the formability limit (FL). In this study, the kinematic effects on the FL of a 5A02-O aluminium alloy in the splitting spinning process were systematically investigated by finite element simulation based on a modified Lemaitre criterion and physical experiments. The results show that at a given roller feed speed or mandrel rotational speed (forming speed), the FL has a nonlinear relationship with forming speed, which increases firstly and then decreases. With the increase of forming speed, the maximum FL decreases, which appears at the larger forming speed. These variations of FL show that there exists a combined effect of the roller feed speed and mandrel rotational speed, thus a ratio between them, named as the roller feed ratio, is then used to investigate FL. It is found that there exists a critical roller feed ratio of approximately 2 mm/rev, independent of the speeds of roller and mandrel. Below this critical value, the FL increases with the roller feed ratio. While over the critical value, the FL decreases. In addition, the decrease of FL becomes more remarkable with the increase of mandrel rotational speed. Furthermore, the variations of stress triaxiality and tensile plastic strain were analyzed to see their effects on FL. The analyses show that the decrease of tensile plastic strain with the increasing roller feed ratio is dominant the increase of FL below the critical roller feed ratio value. The increase in the stress triaxiality is dominant in the decrease of FL when the roller feed ratio is over the critical value in combination with not too high forming speed, whereas both increases are dominant in the decrease of FL when it is over the critical roller feed ratio value in combination with high forming speed. Based on the kinematic effects of mandrel and roller, the process windows of the splitting spinning process were obtained to improve the FL. It is found that under the condition of the roller feed ratio within 1–2.5 mm/rev, the mandrel rotational speed within 8–100 rev/min and the roller feed speed within 0.5–4 mm/s are helpful to get high FL values. The experiments were carried out to verify the prediction on the FL and the process window. The research provides an in-depth understanding of FL and its affecting factors, and thus lays a basis for process optimization and process parameter configuration

Low-energy Scattering of (D∗Dˉ∗)±(D^{*}\bar{D}^{*})^\pm System and the Resonance-like Structure Zc(4025)Z_c(4025)

In this paper, low-energy scattering of the $(D^{*}\bar{D}^{*})^\pm$ meson system is studied within L\"uscher's finite-size formalism using $N_{f}=2$ twisted mass gauge field configurations. With three different pion mass values, the $s$-wave threshold scattering parameters, namely the scattering length $a_0$ and the effective range $r_0$, are extracted in $J^P=1^+$ channel. Our results indicate that, in this particular channel, the interaction between the two vector charmed mesons is weakly repulsive in nature hence do not support the possibility of a shallow bound state for the two mesons, at least for the pion mass values being studied. This study provides some useful information on the nature of the newly discovered resonance-like structure $Z_c(4025)$ observed in various experiments.Comment: 11 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1403.131

Study on TCM Syndrome Differentiation of Primary Liver Cancer Based on the Analysis of Latent Structural Model

Primary liver cancer (PLC) is one of the most common malignant tumors because of its high incidence and high mortality. Traditional Chinese medicine (TCM) plays an active role in the treatment of PLC. As the most important part in the TCM system, syndrome differentiation based on the clinical manifestations from traditional four diagnostic methods has met great challenges and questions with the lack of statistical validation support. In this study, we provided evidences for TCM syndrome differentiation of PLC using the method of analysis of latent structural model from clinic data, thus providing basis for establishing TCM syndrome criteria. And also we obtain the common syndromes of PLC as well as their typical clinical manifestations, respectively

The clinical efficacy of ozone combined with steroid in the treatment of discogenic low back pain: a randomized, double-blinded clinical study

ObjectiveThis randomized double-blinded clinical study is to investigate the clinical efficacy of per-paravertebral disk ozone injection combined with steroids in the treatment of patients with chronic discogenic low back pain (CDLBP).MethodsGroup A (N = 60) received a per-paravertebral injection of a steroid mixture of 10 mL with pure oxygen 20 mL, while group B (N = 60) received a per-paravertebral injection of a steroid mixture of 10 mL combined with ozone 20 mL (30 μg/mL). Injections were administered once a week for 3 weeks, with a follow-up of 6 months. Clinical outcomes were assessed at week 1, month 3, and month 6 with the help of Visual Analog Scale (VAS) scores and Macnab efficacy evaluation.ResultsThe VAS score of both group A (1.65 vs. 6.87, p = 0.000) and group B (1.25 vs. 6.85, p = 0.000) at week 1 was significantly reduced compared to baseline. The effect was sustained at the 3- and 6-month follow-up periods (p < 0.05). Group B had significantly lower VAS scores at month 3 (1.53 vs. 3.82, p = 0.000) and month 6 (2.80 vs. 5.05, p = 0.000) compared to group A, respectively. Based on Macnab criteria, 95 and 96.7% of patients in groups A and B had good rates “excellent plus good” at week 1, respectively. Good rates were significantly higher in group B at month 3 (91.7 vs. 78.3%, p = 0.041) and month 6 (85.0 vs. 68.3%, p = 0.031) compared to group A, respectively. No serious adverse events were noted in both groups.ConclusionPer-paravertebral injection of steroid and ozone combination resulted in better relief of CDLBP compared to pure oxygen plus steroid.Clinical Trial RegistrationChiCTR2100044434 https://www.chictr.org.cn/showproj.html?proj=121571

Parallel momentum distribution of the 28^{28}Si fragments from 29^{29}P

Distribution of the parallel momentum of $^{28}$Si fragments from the breakup of 30.7 MeV/nucleon $^{29}$P has been measured on C targets. The distribution has the FWHM with the value of 110.5 $\pm$ 23.5 MeV/c which is consistent quantitatively with Galuber model calculation assuming by a valence proton in $^{29}$P. The density distribution is also predicted by Skyrme-Hartree-Fock calculation. Results show that there might exist the proton-skin structure in $^{29}$P.Comment: 4 pages, 4 figure

Low-energy Scattering of (DDˉ∗)±(D\bar{D}^{*})^\pm System And the Resonance-like Structure Zc(3900)Z_c(3900)

In this exploratory lattice study, low-energy scattering of the $(D\bar{D}^{*})^\pm$ meson system is analyzed using lattice QCD with $N_f=2$ twisted mass fermion configurations with three pion mass values. The calculation is performed within single-channel L\"uscher's finite-size formalism. The threshold scattering parameters, namely the scattering length $a_0$ and the effective range $r_0$, for the $s$-wave scattering in $J^P=1^+$ channel are extracted. For the cases in our study, the interaction between the two charmed mesons is weakly repulsive. Our lattice results therefore do not support the possibility of a shallow bound state for the two mesons for the pion mass values we studied. This calculation provides some useful information on the nature of the newly discovered resonance-like structure $Z_c(3900)$ by various experimental groups.Comment: 14 pages, 6 figures. Version accepted by PR