轮式移动机器人瞬态模型鲁棒自适应同步终端滑模编队控制 (Robust adaptive synchronized formation control for the transient model of wheeled mobile robots with terminal sliding mode)

In the cooperative formation of wheeled mobile robots, the problem how to guarantee that mobile robots can track their own trajectories while synchronizing motions with others puts forward higher requirements on the design of control algorithms. A robust adaptive synchronized control with terminal sliding mode based on the algebraic graph theory is developed to solve this problem. Firstly, the nonlinear kinematics transient model of wheeled mobile robot is introduced. This model avoids the problem of multi-input coupling mutual interference in general kinematics model. Then, the synchronized control algorithm is designed according to the cross-coupling errors to realize the motion synchronization, and the external disturbance of the system is suppressed by the robust control. The adaptive law ensures the real-time adjustment of the switching gain. The stability analysis is carried out by using the Lyapunov method, which proves the convergence of the system tracking errors. Finally, the effectiveness of the designed algorithm is verified by MATLAB simulation

Evaluation of Performance of Different Methods in Detecting Abrupt Climate Changes

We compared and evaluated the performance of five methods for detecting abrupt climate changes using a time series with artificially generated abrupt characteristics. Next, we analyzed these methods using annual mean surface air temperature records from the Shenyang meteorological station. Our results show that the moving t-test (MTT), Yamamoto (YAMA), and LePage (LP) methods can correctly and effectively detect abrupt changes in means, trends, and dynamic structure; however, they cannot detect changes in variability. We note that the sample size of the subseries used in these tests can affect their results. When the sample size of the subseries ranges from one-quarter to three-quarters of the jump scale, these methods can effectively detect abrupt changes; they perform best when the sample size is one-half of the jump scale. The Cramer method can detect abrupt changes in the mean and trend of a series but not changes in variability or dynamic structure. Finally, we found that the Mann-Kendall test could not detect any type of abrupt change. We found no difference in the results of any of the methods following removal of the mean, creation of an anomaly series, or normalization. However, detrending and study period selection affected the results of the Cramer and Mann-Kendall methods; in the latter case, they could lead to a completely different result

Effect and safety of combined Gegen Qinlian decoction/metformin in the treatment of diabetes mellitus in patients, and its influence on serum C peptide and glycosylated hemoglobin

Purpose: To investigate the clinical efficacy and safety of combined Gegen Qinlian decoction /metformin in the treatment of diabetes mellitus (DM), and its influence on serum C peptide and glycosylated hemoglobin (HbAlc).Methods: One hundred and eighty-six DM patients who received treatment in Tangshan Gongren Hospital, Tangshan City, China from July 2018 to November 2019 were randomly assigned to group X (n = 93) and group Y (n = 93). Group Y was given metformin, while X received a combination of Gegen Qinlian decoction and metformin. Total effectiveness, incidence of adverse reactions, blood glucose, TCM syndrome scores, as well as serum C peptide and HbAlc were determined and compared between the two groups.Results: Compared with group Y, group X had significantly higher treatment effectiveness (p < 0.05), lower incidence of adverse reactions (p < 0.05), significantly lower levels of blood glucose and TCM syndrome score after treatment (p < 0.001), but significantly higher serum C-peptide levels (p < 0.001) and lower levels of HbAlc.Conclusion: the combination of Gegen Qinlian decoction and metformin produces a good anti-diabetic efficacy, with a lower incidence of adverse reactions in patients. Therefore, the combined therapy has potentials for application in clinical practice, but further clinical trials are required

Analysis of Contact Surface Wear Performance of O-Ring Dynamic Seal Based on Archard Model

With the development of hydraulic system to high pressure gradually, the leakage risk of sealing system increases, and it is necessary to confirm the performance parameters of sealing structure through analysis and calculation. The traditional analysis of the friction and wear performance of the seal ring is limited to the amount of wear, and cannot describe the surface wear characteristics of the O-ring in detail. Based on the Archard model, this paper constructs a model to analyse and calculate the friction and wear performance of the dynamic seal structure through the material characteristics and operating parameters, analyses the friction and wear characteristics of the O-ring seal structure under different compression ratio, medium pressure, relative slip velocity and temperature, and summarizes the influence of each single variable on the wear characteristics of the dynamic seal structure. According to the analysis in this paper, the increase of medium pressure of 5 MPa will cause the wear concentration area of the contact surface to move to the back pressure side, and the overall wear will be reduced, but the increase of contact area will lead to the weakening of sealing effect. By the action of 15 MPa, when the compression ratio is between 5% and 10%, the change of cumulative wear rate and the wear rate of each node is small

Predictive task assignment in spatial crowdsourcing: A data-driven approach

With the rapid development of mobile networks and the widespread usage of mobile devices, spatial crowdsourcing, which refers to assigning location-based tasks to moving workers, has drawn increasing attention. One of the major issues in spatial crowdsourcing is task assignment, which allocates tasks to appropriate workers. However, existing works generally assume the static offline scenarios, where the spatio-temporal information of all the workers and tasks is determined and known a priori. Ignorance of the dynamic spatio-temporal distributions of workers and tasks can often lead to poor assignment results. In this work we study a novel spatial crowdsourcing problem, namely Predictive Task Assignment (PTA), which aims to maximize the number of assigned tasks by taking into account both current and future workers/tasks that enter the system dynamically with location unknown in advance. We propose a two-phase data-driven framework. The prediction phase hybrids different learning models to predict the locations and routes of future workers and designs a graph embedding approach to estimate the distribution of future tasks. In the assignment component, we propose both greedy algorithm for large-scale applications and optimal algorithm with graph partition based decomposition. Extensive experiments on two real datasets demonstrate the effectiveness of our framework

Shedding New Light on R(D(s)(∗)){\cal R} (D_{(s)}^{(\ast)} ) and ∣Vcb∣|V_{cb}| from Semileptonic Bˉ(s)→D(s)(∗)ℓνˉℓ\bar B_{(s)} \to D_{(s)}^{(\ast)} \ell \bar {\nu}_{\ell} Decays

We compute for the first time the next-to-leading-order QCD corrections to the $\bar B_{(s)} \to D_{(s)}^{(\ast)}$ form factors at large hadronic recoil. Both the charm-quark-mass and the strange-quark-mass dependent pieces can generate the leading-power contributions to these form factors. Including further various power-suppressed contributions, we perform the combined fits of the considered form factors to both our large-recoil theory predictions and the lattice QCD results, thus improving upon the previous determinations of the lepton-flavour-universality ratios ${\cal R} (D^{(\ast)})$ significantly.Comment: 6 pages plus Supplemental Material, 3 figures, 1 table, 2 ancillary file

One-stitch anastomosis through the skin with bicanalicular intubation:a modified approach for repair of bicanalicular laceration

<b>AIM:</b> To evaluate the efficacy and safety of one-stitch anastomosis through the skin with bicanalicular silicone tube intubation in repairing of bicanalicular laceration.<b>METHODS:</b>The clinical data of 15 consecutive patients with both superior and inferior canalicular laceration in one eye who underwent surgical repair using one-stitch anastomosis through the skin and bicanalicular stent were retrospective studied. All the operations were performed under surgical microscope, 5-0 silk sutures were used and were with bicanalicular silicone tube (diameter was 8mm) intubation, for one lacerated canaliculi one-stitch anastomosis through the skin. The stents were left in place for 3 months postoperatively and then removed. The follow-up period was 3 - 36 months (average 14 months).<b>RESULTS:</b>In 15 patients, 13 patients were cured entirely, 1 patient was meliorated, 1 patient with no effects. All patients had got good recovery of eyelid laceration with no traumatic deformity in eyelid and canthus. Complication was seen in one case, for not followed the doctor’s guidance to come back to hospital to had the suture removed on the 7^th day after operation, when he came at the 15^th day, the inferior canalicular wall and eyelid skin were corroded by the suture caused 2mm wound, and the inside silicone tube was exposed, a promptly repair with 10-0 nylon suture was done, the wound healed in a week. There were no early tube protrusions and punctal slits in the patients.<b>CONCLUSION:</b>One-stitch anastomosis through the skin with bicanalicular silicone tube intubation is a good method in repair of bicanalicular laceration in one eye, the cut ends can be anastomosed directly, and with excellent cosmetic results, it is acceptable for the patients. For there is no suture remained in the wound permanently, so there is no suture-related granuloma which may cause obstruction or stenosis of canaliculi. It is simple, economical, effective and safe