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The friction type tensioner is an energy absorbing component in belt drive system which has hysteretic torque and nonlinear damping. In this paper, a hysteretic model is used for describing the tensioner’s operating torque versus the imposed angle, and considered into the dynamic analysis of a belt drive system. The modeling process for calculating the vibration responses of a belt drive system is presented, and two iterative methods are proposed for estimating the tensioner’s nonlinear damping in a varying excitation frequency. One timing belt drive system is taken as a case study. The system’s vibration responses, such as the oscillation angle of tensioner arm, the transmission error between pulleys and the hub load on pulley are calculated and compared with the measured values, which validate the presented methods. The influence of iterative method on the computational efficiency and iterative accuracy are both discussed. At last a modified method is presented to improve iterative efficiency. The presented technique can improve the computational efficiency with a good computational accuracy.

This study aimed to better understand the prognostic effect of multiple genetic markers and identify more subpopulations at ultra high risk of poor outcome in bone marrow (BM) metastatic neuroblastoma (NB).We screened the MYCN, 1p36 and 11q23 loss of heterozygosity (LOH) statuses of 154 patients by interphase fluorescence in situ hybridization of BM cells. The clinical characteristics of patients with the three markers and their associations with prognosis were analysed.MYCN amplification and LOH at 1p36 and 11q23 were identified in 16.2%, 33.1% and 30.5% of patients, respectively. There were strong associations between MYCN amplification and 1p36 LOH as well as 11q23 LOH. Both MYCN amplification and 1p36 LOH were strongly associated with high levels of lactate dehydrogenase (LDH) and neuron-specific enolase, more than 3 metastatic organs, and more events. 11q23 LOH occurred mainly in patients older than 18 months, and those who had high LDH levels. In univariate analysis, patients with MYCN amplification had poorer prognosis than those without. Patients with 1p36 LOH had a 3-year event-free survival (EFS) and overall survival lower than those without. 11q23 LOH was associated with poorer EFS only for patients without MYCN amplification. In a multivariate model, MYCN amplification was independently associated with decreased EFS in all cohorts. 11q23 LOH was an independent prognostic factor for patients without MYCN amplification, whereas 1p36 LOH was not an independent marker regardless of MYCN amplification. Compared with all cohorts, patients with both MYCN amplification and 1p36 LOH had the worst outcome and clinical features.Patients with both MYCN amplification and 1p36LOH had the worst survival rate, indicating an ultra high-risk group. Our results may be applied in clinical practice for accurate risk stratification in future studies.

In the existing studies, the hysteretic model of tensioner is applied in analysis of a belt drive system which can improve the computational accuracy. But the computational efficiency is low and not suitable for system optimization. In this paper, an approach is presented to simplify the tensioner’s hysteretic model into an equivalent stiffness and damping which is used for improving the computational efficiency of vibration responses of the belt drive system. A simplified model and computation method of a belt drive system is established. The hysteretic model of a belt tensioner consists of a linear stiffness and viscous damping based on the averaging energy method to simplify the hysteretic parameters and improve the computational efficiency. The equivalent linear stiffness and damping of the tensioner are estimated using an iterative technique. A timing belt drive system is considered as a case study. The belt system's vibration responses are obtained and compared with the measured results to evaluate the performance of the presented approach. The computational results are compared with a previously published method, and the difference between the proposed method (Method I) and the previously published method (Method II) is discussed. The presented method has the following merits: (1) The linearization of tensioner’s hysteretic model can improve the computational efficiency greatly with an acceptable computational accuracy. (2) The semi-analytic method which is used to derive the system equations can further reduce the amount of computation. It is suitable for parameter optimization of system.

The rapid development of science and technology promotes the intensive development of robotics and the application of ADAMS in the field of robotics is constantly expanding. Research on robot kinematics and dynamics is the core issue of biped robot animation simulation. It is of great significance to propose an efficient and improved inverse kinematics algorithm for the development of robotic bionics in China. In this paper, the BIOLOID robot assembly kit is used as the research platform. Based on this, the biped robot kinematics equations and dynamic equations are deduced, and a three-step programming method is used to carry out reasonable gait planning for the biped robot. A simplified virtual prototype model of the lower limb of a biped robot, and the motion trajectories of the joints are input to perform motion simulation of the robot’s static walking. The feasibility of gait planning is verified by analyzing the dynamic images obtained from the simulation experiments and the experimental data of each joint vector. This paper uses the Denavit-Hartenberg rule to construct a biped robot animation simulation kinematics model, deduces a matrix expression describing joint vectors between adjacent links, and solves the biped robot’s positive kinematics equation by chain multiplication rule; An efficient and improved inverse kinematics algorithm is proposed. This solution has the characteristics of high accuracy, high efficiency and few redundant solutions. The experimental study found that the three-step planning method for biped robotic static walking planning is feasible and can reach 98%, and can meet the pre-planning requirements.

Age estimation based on the mineralized morphology of teeth is one of the important elements of forensic anthropology. To explore the most suitable age assessment protocol for adolescents in the South China population, 1477 panoramic radiographs images of people aged 2–18 years in the South were collected and staged by the Demirjian mineralization staging method. The dental age were estimated using the parameters of the Demirjian and Willems. Mathematical optimization and machine learning optimization were also performed in the data processing process in an attempt to obtain a more accurate model. The results show that Willems' method is more accurate in estimating the dental age of the South China population, while the model can be further optimized by re-assigning the model through a non-intercept regression method. The machine learning model presented excellent results in terms of the efficacy comparison results with the traditional mathematical model, and the machine learning model under the Boosting framework such as Gradient Boosting Decision Tree (GBDT) significantly reduced the error in dental age estimation compared to the traditional mathematical method. This machine learning processing method based on traditional assessment data can effectively reduce the error of assessment while saving arithmetic power. This study demonstrates the effectiveness of the GBDT algorithm in optimizing forensic age estimation models and provides a reference for other regions to use this scheme for age assessment model architecture, also the lightweight nature of machine learning offers the possibility of widespread forensic anthropological age estimation.

To find a method to distinguish exogenous gamma-hydroxybutyrate (GHB) from endogenous GHB by establishing ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) based on exosome for quantitative detection of GHB in the rat blood.Adult male SD rats were divided into 1 h, 5 h, 10 h administration group and control group. After 1 h, 5 h and 10 h of single precursor of GHB gamma-butyrolactone (GBL) intraperitoneal injection in administration groups, 5 mL blood was collected from the abdominal aorta. Meanwhile, the control group was given a same dose of normal saline, and 5 mL blood was collected at 1 h. Among the 5 mL blood, 0.5 mL was directly detected by HPLC-MS after pretreatment, and exosomes were extracted from the remaining blood by differential centrifugation and detected.The concentration of GHB in the control group was (87.36±33.48) ng/mL, and the concentration with administration at 1 h, 5 h and 10 h was (110 400.00±1 766.35) ng/mL, (1 479.00±687.01) ng/mL and (133.60±12.17) ng/mL, respectively. The results of exosome detection showed that no peak GHB signal was detected in the control group and the 10 h administration group, and the concentrations of GHB at 1 h and 5 h administration groups were (91.47±33.44) ng/mL and (49.43±7.05) ng/mL, respectively.GHB was detected in blood exosome by UPLC-MS, which indicated that exogenous GHB could be detected in plasma exosomes, while endogenous GHB could not be detected, suggesting that this method may be used as a basis to determine whether there is exogenous drug intake.

Methamphetamine (METH) abuse is a significant public health concern globally. Cardiac toxicity is one of the important characteristics of METH, in addition to its effects on the nervous system. However, to date, research on the cardiotoxic injury induced by METH consumption has been insufficient. To systematically analyze the potential molecular mechanism of cardiac toxicity in METH-associated heart failure (HF), a rat model was constructed with a dose of 10 mg/kg of METH consumption. Cardiac function was evaluated by echocardiography, and HE staining was used to clarify the myocardial histopathological changes. Integrated analyses, including mRNA, miRNA and lncRNA, was performed to analyze the RNA expression profile and the potential molecular mechanisms involved in METH-associated HF. The results showed that METH caused decreased myocardial contractility, with a decreased percent ejection fraction (%EF). Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses of the RNAs with expression changes revealed abnormal circadian rhythm regulation in the METH groups, with circadian rhythm-related genes and their downstream effectors expressed differentially, especially the aryl hydrocarbon receptor nuclear translocator-like (Arntl). Competing endogenous RNA (ceRNA) networks associated with circadian rhythm, including Arntl, was also observed. Therefore, this study revealed that long-term METH consumption was associated with the HF in a rat model by decreasing the %EF, and that the abnormal circadian rhythm could provide new directions for investigating the METH-associated HF, and that the differentially expressed genes in this model could provide candidate genes for the identification and assessment of cardiac toxicity in METH-associated HF, which is fundamental for further understanding of the disease.