Adaptive Initialization Method Based on Spatial Local Information for k

k-means algorithm is a widely used clustering algorithm in data mining and machine learning community. However, the initial guess of cluster centers affects the clustering result seriously, which means that improper initialization cannot lead to a desirous clustering result. How to choose suitable initial centers is an important research issue for k-means algorithm. In this paper, we propose an adaptive initialization framework based on spatial local information (AIF-SLI), which takes advantage of local density of data distribution. As it is difficult to estimate density correctly, we develop two approximate estimations: density by t-nearest neighborhoods (t-NN) and density by ϵ-neighborhoods (ϵ-Ball), leading to two implements of the proposed framework. Our empirical study on more than 20 datasets shows promising performance of the proposed framework and denotes that it has several advantages: (1) can find the reasonable candidates of initial centers effectively; (2) it can reduce the iterations of k-means’ methods significantly; (3) it is robust to outliers; and (4) it is easy to implement

Corneal Surface Ablation Laser Refractive Surgery for the Correction of Myopia: A Network Meta-analysis

PURPOSE: To systematically compare the efficacy, predictability, safety, postoperative haze, pain scores, and epithelial healing time of four corneal surface ablation procedures. METHODS: PubMed, Embase, Cochrane Library, and the U.S. trial registry were searched up to June 2018. Randomized controlled trials were selected. Efficacy (uncorrected distance visual acuity of 20/20 or better), predictability (refractive spherical equivalent within ±0.50 diopters [D] of the target), and safety (loss of two or more lines of spectacle corrected distance visual acuity) were set as primary outcome measures. Haze, pain scores, and epithelial healing time were set as secondary outcome measures. RESULTS: Eighteen studies involving 1,423 eyes were included. According to the Grading of Recommendations Assessment, Development, and Evaluation, the quality of outcomes were moderate to high (70.6%). There were no differences in efficacy, predictability, safety, haze, day 1 pain, and epithelial healing time between treatments. Epithelial laser in situ keratomileusis (epi-LASIK) had statistically significantly higher pain scores on day 3 compared to photorefractive keratectomy (PRK) (weighted mean differences [WMD] = 2.2, 95% credible intervals [CrI] = 0.19 to 4.01) and transepithelial PRK (T-PRK) (WMD = 2.7, 95% CrI = 0.51 to 4.84). The surface under the cumulative ranking curve ranking results (best to worst) showed laser epithelial keratomileusis (LASEK) ranked highest for efficacy, predictability, safety, and day 1 pain scores. Epi-LASIK ranked best for grade 1 haze scores. T-PRK ranked best for haze of 0.5 or higher, haze scores day 3 pain scores, and epithelial healing time. CONCLUSIONS: Surface laser refractive surgeries are comparable in terms of efficacy, predictability, safety, and postoperative haze except for day 3 pain scores, with epi-LASIK being more painful compared to PRK and T-PRK. [J Refract Surg. 2018;34(11):726-735.]

Multi-modes control method for spacecraft formation establishment and reconfiguration near the libration points

AbstractThis paper studies Multi-modes control method for libration points formation establishment and reconfiguration. Firstly, relations between optimal impulse control and Floquet modes are investigated. Method of generating modes is proposed. Characteristics of the mode coefficients stimulated at different time are also given. Studies show that coefficients of controlled modes can be classified into four types, and formation establishment and reconfiguration can be achieved by multi-impulse control with the presented method of generating modes. Then, since libration points formation is generally unstable, mutli-modes keeping control method which can stabilize five Floquet modes simultaneously is proposed. Finally, simulation on formation establishment and reconfiguration are carried out by using method of generating modes and mutli-modes keeping control method. Results show that the proposed control method is effective and practical

A Study On Gold Nanoparticle Synthesis Using Oleylamine As Both Reducing Agent And Protecting Ligand

The growth kinetics and mechanism of a gold nanoparticle synthesis using water as a single phase solvent and oleylamine as both reducing agent and monolayer protection agent were studied. FT-IR and 1H NMR spectroscopic analysis revealed a conversion of oleylamine ligands to oleylamides when gold(III) was reduced to gold(I) and gold atoms. During the reaction, it was found by UV-Vis absorption spectroscopy and transmission electron microscopic study that oleylamine ligands formed large complex aggregates with gold salt instantly upon mixing these two agents together. At an elevated temperature of 80°C, the complex decomposed first into very small particles and then the small particles recombined together into larger and thermally stable particles with an average core size around 9-10 nm. The oleylamide ligands formed a protecting monolayer around the nanoparticles through a hydrogen bonding network between the amide groups. The recombination of small particles into larger ones was found to follow a logistic model, as confirmed by a nonlinear regression fitting of the UV-Vis absorption data of the reaction solution with the mathematical model. Copyright © 2007 American Scientific Publishers All rights reserved

Solid Phase Monofunctionalization Of Gold Nanoparticles Using Ionic Exchange Resin As Polymer Support

A solid phase modification method using anionic exchange resin as polymer support was developed for the synthesis of monofunctional gold nanoparticles. Based on a catch and release mechanism to control the number of functional groups attached to the nanoparticle surface, bifunctional thiol ligands with a carboxylic acid end group were first immobilized at a controlled density on anionic exchange resin through electrostatic interactions. Gold nanoparticles were then immobilized to the anionic exchange resin by a one-to-one place exchange reaction between resin-bound thiol ligands and butanethiol-protected gold nanoparticles in solution. After cleaving off from the resin under mild conditions, gold nanoparticles with a single carboxyl group attached to the surface were obtained as the major product. Experimental conditions such as the solvents used for ligand loading and solid phase place exchange reaction, and the loading density of the ligands, were found to play a critical role towards the successful synthesis of monofunctional nanoparticles. Overall, the noncovalent bond-based ligand immobilization technique reported here greatly simplified the process of solid phase monofunctionalization of nanoparticles compared to a previously reported covalent bondbased ligand immobilization technique. Copyright © 2007 American Scientific Publishers All rights reserved

Monofunctional Gold Nanoparticles Prepared Via A Noncovalent-Interaction-Based Solid-Phase Modification Approach

The solid-phase preparation of monofunctionalized gold nanoparticles using noncovalent interaction was presented. The solid support used in this preparation was amino-group functionalized silica gel. The bifunctional ligands, 11-mercaptoundecanoic acid (MUA), were then loaded onto the support directly as a result of the electrostatic interaction of the positively charged amino groups from the silica gel with the negatively charged carboxylic acid groups from the MUA ligands. The nanoparticle was purified by washing with petroleum ether, followed by gel permeation chromatography to give 60-90 % yield of monocarboxyl gold nanoparticles. In addition to amino-group-functionalized silica gel, Rink resin, an amino-group-functionalized resin consisting of a lightly crosslinked polystyrene matrix, was also used for the surface functionalization of the gold nanoparticles. The most reliable method of determining the relative purity of the monofunctional nanoparticle product is by conducting a dimine-coupling reaction with the solid-phase-modified nanoparticles and using TEM to analyze the coupled product

Monofunctional Gold Nanoparticles Prepared via a Noncovalent‐Interaction‐Based Solid‐Phase Modification Approach

The solid-phase preparation of monofunctionalized gold nanoparticles using noncovalent interaction was presented. The solid support used in this preparation was amino-group functionalized silica gel. The bifunctional ligands, 11-mercaptoundecanoic acid (MUA), were then loaded onto the support directly as a result of the electrostatic interaction of the positively charged amino groups from the silica gel with the negatively charged carboxylic acid groups from the MUA ligands. The nanoparticle was purified by washing with petroleum ether, followed by gel permeation chromatography to give 60-90 % yield of monocarboxyl gold nanoparticles. In addition to amino-group-functionalized silica gel, Rink resin, an amino-group-functionalized resin consisting of a lightly crosslinked polystyrene matrix, was also used for the surface functionalization of the gold nanoparticles. The most reliable method of determining the relative purity of the monofunctional nanoparticle product is by conducting a dimine-coupling reaction with the solid-phase-modified nanoparticles and using TEM to analyze the coupled product

Research on Precise Tracking Control of Gear-Shifting Actuator for Non-Synchronizer Automatic Mechanical Transmission Based on Sleeve Trajectory Planning

The Non-Synchronizer Automated Mechanical Transmission (NSAMT) demonstrates a straightforward structure and cost-effectiveness; however, the primary obstacle to its widespread application lies in NSAMT shift control. The implementation of active angle alignment effectively addresses the issue of shifting quality, but achieving active angle alignment necessitates precise tracking of the planned shifting curve by the gear-shifting actuator. To tackle the control problem of accurate tracking for NSAMT shift actuators, this paper initially analyzes the structure and shift characteristics of the NSAMT. Based on this analysis, a physical model is established using Amesim, incorporating a drive motor, two-gear NSAMT, shift actuator, sleeve, and DC motor model. An extended state observer (ESO) is designed to mitigate unknown interference within the system. Furthermore, an active angle alignment control algorithm based on “zero speed difference” and “zero angle difference” for double target tracking is constructed while planning the axial motion trajectory of the sleeve. The Backstepping algorithm is employed to successfully track and regulate this planned trajectory. Finally, through Hardware-in-the-Loop testing, we validate our proposed control strategy, which demonstrates consistent results with simulation outcomes, thereby affirming its effectiveness

The reconstruction of fingertip injury by mini hallux toenail flap pedicled with the hallux transverse artery and toe pulp vein transplantation technique based on the equivalent design theory

Abstract Introduction How to reconstruct the damaged fingertip is a clinical problem. Our team propose the theory of equivalent design and use the mini toenail flap pedicled with the hallux transverse artery and toe pulp vein transplantation technique to reconstruct Allen’s type II fingertip injury. Thus, we perform the retrospective study to evaluate the effects of this technique on fingertip injury. Materials and methods A retrospective analysis was performed on 56 patients admitted to our hospital from January 2015 to January 2020 who used equivalently designed miniature hallux toenail flaps for the plastic repair of fingertip damage. We recorded the size of the miniature hallux toenail flap, operation time, intraoperative blood loss, and complications and calculated the survival rate of the transplanted miniature hallux toenail flap. During routine follow-up after surgery, we recorded nail growth time and observed finger appearance. At the last time of follow-up, we recorded Semmes-Weinstein evaluating tactile sensation and Two-point discrimination testing (TPD). The efficacy was evaluated by Zook score evaluation. Results The size of the mini hallux toenail flap was 0.71 cm × 1.22 cm to 0.88 cm × 1.71 cm. The operation time was (3.54 ± 0.58) hours, the intraoperative blood loss was (20.66 ± 4.87) ml, and the survival rate of mini hallux toenail flaps was 100%. The postoperative follow-up time was (30.82 ± 11.21) months, and the total nail growth time was (9.68 ± 2.11) months. The average tactile sensation evaluated by the Semmes-Weinstein test was (0.32 ± 0.14) g, and the average TPD was (7.33 ± 1.02) mm. According to Zook score, the curative effect of fifty-six cases were all excellent or good with 100% excellent and good rate, and all patients had beautiful appearances and good function of damaged fingertips. Conclusions Based on the equivalent design theory, the mini hallux toenail flap pedicled with the hallux transverse artery and toe pulp vein transplantation technique is an effective method to reconstruct Allen’s type II fingertip injury with a beautiful appearance and good function. Type of study/level of evidence Therapeutic IV