Application of nanotechnology in a silver/graphite contact material and optimization of its physical and mechanical properties

By applying nanotechnology, a new type of silver/graphite (AgC) electricalcontact was fabricated and characterized. The AgC coating powders were obtained through high-energyball milling and reducer liquid spraying-coating method. The as-prepared powders were examined bytransmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray diffraction(XRD). The results show that the thickness of graphite flakes milled for 10 h is about 50-60 nm andthe AgC coating powders exhibit flocculent structure with quite fine and homogeneous internalmicropores. XRD implies that the average crystalline size of silver in coating powders is about 50nm. The mechanical and physical properties of this newly developed AgC contact made from theabove-mentioned nanocrystalline powders by traditional powder metallurgy technique were measured.Compared with its counterparts made from other techniques, the properties of this new AgC contacthave been optimized. High surface energy and high-energy interfaces of the nanocrystalline AgCcoating powders provide powerful driving force for sintering densification. Moreover, the flocculentstructure of the powders is also an important factor to acquire fine density ratio.

Reduced Differential Transform Method for Solving Nonlinear Biomathematics Models

In this paper,we study the approximate solutions for some of nonlinear Biomathematics models via the e-epidemic SI1I2R model characterizing the spread of viruses in a computer network and SIR childhood disease model.The reduced differential transforms method(RDTM)is one of the interesting methods for finding the approximate solutions for nonlinear problems.We apply the RDTM to discuss the analytic approximate solutions to the SI1I2R model for the spread of virus HCV-subtype and SIR childhood disease model.We discuss the numerical results at some special values of parameters in the approximate solutions.We use the computer software package such as Mathematical to find more iteration when calculating the approximate solutions.Graphical results and discussed quantitatively are presented to illustrate behavior of the obtained approximate solutions.

Dynamical Behaviors of Nonlinear Coronavirus (COVID-19) Model with Numerical Studies

The development of mathematical modeling of infectious diseases is a key research area in various elds including ecology and epidemiology.One aim of these models is to understand the dynamics of behavior in infectious diseases.For the new strain of coronavirus(COVID-19),there is no vaccine to protect people and to prevent its spread so far.Instead,control strategies associated with health care,such as social distancing,quarantine,travel restrictions,can be adopted to control the pandemic of COVID-19.This article sheds light on the dynamical behaviors of nonlinear COVID-19 models based on two methods:the homotopy perturbation method(HPM)and the modied reduced differential transform method(MRDTM).We invoke a novel signal ow graph that is used to describe the COVID-19 model.Through our mathematical studies,it is revealed that social distancing between potentially infected individuals who are carrying the virus and healthy individuals can decrease or interrupt the spread of the virus.The numerical simulation results are in reasonable agreement with the study predictions.The free equilibrium and stability point for the COVID-19 model are investigated.Also,the existence of a uniformly stable solution is proved.

BRIEF ARTICLE New reduced volume preparation regimen in colon capsule endoscopy

AIM:To evaluate the effectiveness of our proposed bowel preparation method for colon capsule endoscopy.METHODS:A pilot,multicenter,randomized controlled trial compared our proposed "reduced volume method"(group A) with the "conventional volume method"(group B) preparation regimens.Group A did not drink polyethylene glycol electrolyte lavage solution(PEGELS) the day before the capsule procedure,while group B drank 2 L.During the procedure day,groups A and B drank 2 L and 1 L of PEG-ELS,respectively,and swallowed the colon capsule(PillCam COLON capsule).Two hours later the first booster of 100 g magnesium citrate mixed with 900 mL water was administered to both groups,and the second booster was administered six hours post capsule ingestion as long as the capsule had not been excreted by that time.Capsule videos were reviewed for grading of cleansing level,RESULTS:Sixty-four subjects were enrolled,with results from 60 analyzed.Groups A and B included 31 and 29 subjects,respectively.Twenty-nine(94%) subjects in group A and 25(86%) subjects in group B had adequate bowel preparation(ns).Twenty-two(71%) of the 31 subjects in group A excreted the capsule within its battery life compared to 16(55%) of the 29 subjects in group B(ns).Of the remaining 22 subjects whose capsules were not excreted within the battery life,all of the capsules reached the left side colon before they stopped functioning.A single adverse event was reported in one subject who had mild symptoms of nausea and vomiting one hour after starting to drink PEG-ELS,due to ingesting the PEG-ELS faster than recommended.CONCLUSION:Our proposed reduced volume bowel preparation method for colon capsule without PEG-ELS during the days before the procedure was as effective as the conventional volume method.

Reduced Differential Transform Method for Solving Linear and Nonlinear Goursat Problem

In this paper a new method for solving Goursat problem is introduced using Reduced Differential Transform Method (RDTM). The approximate analytical solution of the problem is calculated in the form of series with easily computable components. The comparison of the methodology presented in this paper with some other well known techniques demonstrates the effectiveness and power of the newly proposed methodology.

Exact Solutions of(2+1)-Dimensional HNLS Equation

In this paper, we use the classical Lie group symmetry method to get the Lie point symmetries of the （2＋1）-dimensional hyperbolic nonlinear Schr6dinger （HNLS） equation and reduce the （2＋1）-dimensional HNLS equation to some （1 ＋ 1 ）-dimensional partial differential systems. Finally, many exact travelling solutions of the （2＋1）-dimensional HNLS equation are obtained by the classical Lie symmetry reduced method.

Studies on Reduced Extent Method for Inhibited Thermokinetics Of Enzyme－Catalyzed Reaction──Inhibition of the laccase－catalyzed oxidation of o－dihydroxybenzene by m－dihydroxybenzene

The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distingushing inhibition type was given and the methods for calculating kinetic parameters, KM,Ki and Urn were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation of o-dihydroxybenzene by m-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type, KM=6.224×10-3 mol L-1, Ki=2. 363 × 10-2 mol. L-1.

Reduced Expanding Load Method for Simulation-Based Structural System Reliability Analysis

The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method (RELM) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaches,RELM method gives a much better understanding of structural failure frequency and its reliability index β is more meaningful.To illustrate this new idea, a specific example is given.

An efficient technique for recovering responses of parameterized structural dynamic problems

In this article,an effective technique is developed to efficiently obtain the output responses of parameterized structural dynamic problems.This technique is based on the conception of reduced basis method and the usage of linear interpolation principle.The original problem is projected onto the reduced basis space by linear interpolation projection,and subsequently an associated interpolation matrix is generated.To ensure the largest nonsingularity,the interpolation matrix needs to go through a timenode choosing process,which is developed by applying the angle of vector spaces.As a part of this technique,error estimation is recommended for achieving the computational error bound.To ensure the successful performance of this technique,the offline-online computational procedures are conducted in practical engineering.Two numerical examples demonstrate the accuracy and efficiency of the presented method.

Antioxidant Activity Evaluation in a Series of Heterocyclic Compounds Derived from 1,8-Diaminonaphthalene

From (2,3-dihydro-1H-perimidin-2-yl)-phenyl, the substitution of OH group in ortho or para position on the phenyl ring, allows us to synthesize the studied compounds. These three compounds have been characterized by conventional spectroscopic methods (NMR and MS). The interest of this work is to review the antioxidant activity of our compounds. The antioxidant activity screening carried out according to FRAP and DPPH methods revealed significant anti-free radical properties for compounds 1 and 2 even at low concentrations. In contrast to the compound 2, compound 3 for which the OH group is substituted in para position has the lowest activity in both cases. Therefore the para position seems to be the least sensitive position to increase the antioxidant activity of this pharmacophore.

Application of the Generalized Reduced Gradient Method in Mechanical Optimization Design

This paper presents the generalized reduced gradient method （GRG） and its realization forms. The application example of GRG in the optimization design of a single-stage cylindrical gear reducer is introduced. The algo- rithm of the GRG method is realized in Vissim software. Based on the mathematical model of the single-stage cylin- drical gear reducer, the simulation structure of the optimization design was achieved. The experiment results show that the GRG method has fewer iterations and higher precision. The GRG method is very suitable for solving mechanical optimization design.

Acupuncture at Nèiguān(内关 PC 6) in combination with respiratory reinforcing and reducing method for 38 cases of cardiac neurosis

Objective To observe the clinical effect of acupuncture at Neiguan （内关 PC 6） in combination with respiratory reinforcing and reducing method for treatment of cardiac neurosis. Methods Thirty-eight patients with cardiac neurosis were selected for treatment through acupuncture at PC 6 in combination with respiratory reinforcing and reducing method. With twice per day, treated for 6 days per week, and 4 weeks as one course, the therapeutic effect was assessed after one course. Results Twenty-one cases were cured, 15 cases were remarkably improved, and 2 cases were failed. The total effective rate was 94.7%. Conclusion Acupuncture at PC 6 in combination with respiratory reinforcing and reducing method is effective in treatment of cardiac neurosis.

Observation on lower-reinforcing and upper- reducing acupuncture method for hyperplasia of mammary gland and its influence on estradiol and progesterone

Objective： To observe the clinical effect of lower-reinforcing and upper-reducing acupuncture method for hyperplasia of mammary gland （HMG） and its influence on estradiol （E2） and progesterone （P）. Methods： A randomized, single-blinded and controlled trial was conducted. A total of 124 cases conforming to the inclusion criteria were randomized by random number table into a treatment group and a control group, with 62 cases in each group. Patients in both groups received acupuncture therapy at the same acupoints, while patients in the treatment group received lower-reinforcing and upper-reducing method, and patients in the control group received even reinforcing-reducing manipulation. The treatment started around 10 d before menstruation and was conducted every other day. Patients received 5 treatments in each menstruation cycle for consecutive 3 cycles. The levels of E2, P and E2/P and clinical efficacy were measured before and after treatment. Results： After treatment, the breast lump size, pain intensity and concomitant symptoms score in both groups were substantially lower than those before treatment, showing statistical significances （all P〈0.01）, and the improvement in the treatment group was higher than that in the control group, and the between-group comparisons showed statistical significances （all P〈0.01）. After treatment, the overall effective rate was 91.9% in the treatment group, higher than 72.6% in the control group, and the between-group comparison showed a statistical significance （P〈0.01）. After treatment, levels of E2, P and E2/P value showed no statistical significance when compared with those before treatment in the two groups （all P〉0.05）. Conclusion： Lower-reinforcing and upper-reducing acupuncture method can effectively alleviate clinical symptoms and signs in HMG patients, and produce a better effect than even reinforcing-reducing manipulation. The majority of HMG patients＇ E2, P level and E2/P value were not beyond the normal ranges; therefore, acupuncture showed no substantial influence on E2 and P levels and E2/P value.

Acupuncture with twirling reducing method for tinnitus of excessive liver-fire type: a clinical observation

Objective To observe the clinical efficacy of acupuncture with twirling reducing method for tinnitus of excessive liver-fire type.Methods One hundred and one patients with tinnitus of excessive liver-fire type were randomly divided into a twirling reducing method group(35 cases),a needle retaining group(33 cases)and

Multibody system transfer matrix method:The past, the present, and the future

The multibody system transfer matrix method(MSTMM),a novel dynamics approach developed during the past three decades,has several advantages compared to conventional dynamics methods.Some of these advantages include avoiding global dynamics equations with a system inertia matrix,utilizing low‐order matrices independent of system degree of freedom,high computational speed,and simplicity of computer implementation.MSTMM has been widely used in computer modeling,simulations,and performance evaluation of approximately 150 different complex mechanical systems.In this paper,the following aspects regarding MSTMM are reviewed:basic theory,algorithms,simulation and design software,and applications.Future research directions and generalization to more applications in various fields of science,technology,and engineering are discussed.

Reduced Basis Approaches in Time-Dependent Non-Coercive Settings for Modelling the Movement of Nuclear Reactor Control Rods

In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrical framework.In particular,in a first approach,a piece-wise affine transformation based on subdomains division has been implemented for modelling the movement of one control rod.In the second approach,a“staircase”strategy has been adopted for simulating themovement of all the three rods featured by the nuclear reactor chosen as case study.The neutron kinetics has been modelled according to the so-called multi-group neutron diffusion,which,in the present case,is a set of ten coupled parametrized parabolic equations(two energy groups for the neutron flux,and eight for the precursors).Both the reduced order models,developed according to the two approaches,provided a very good accuracy comparedwith high-fidelity results,assumed as“truth”solutions.At the same time,the computational speed-up in the Online phase,with respect to the fine“truth”finite element discretization,achievable by both the proposed approaches is at least of three orders of magnitude,allowing a real-time simulation of the rod movement and control.

Non-Intrusive Reduced OrderModeling of Convection Dominated Flows Using Artificial NeuralNetworkswithApplication to Rayleigh-Taylor Instability

.A non-intrusive reduced order model(ROM)that combines a proper orthogonal decomposition(POD)and an artificial neural network(ANN)is primarily studied to investigate the applicability of the proposed ROM in recovering the solutions with shocks and strong gradients accurately and resolving fine-scale structures efficiently for hyperbolic conservation laws.Its accuracy is demonstrated by solving a high-dimensional parametrized ODE and the one-dimensional viscous Burgers’equation with a parameterized diffusion coefficient.The two-dimensional singlemode Rayleigh-Taylor instability(RTI),where the amplitude of the small perturbation and time are considered as free parameters,is also simulated.An adaptive sampling method in time during the linear regime of the RTI is designed to reduce the number of snapshots required for POD and the training of ANN.The extensive numerical results show that the ROM can achieve an acceptable accuracy with improved efficiency in comparison with the standard full order method.

Treatment of 76 Cases of Sinusitis with Acupuncture

Sinusitis is a prevalent nasal disease, characterized by profuse turbid nasal discharge, usually coupled with headache, nasal stuffiness, declining of smell, and also dizziness in protracted cases. The author treated 76 cases by acupuncture, and it was reported as follows.

REDUCED BASIS METHOD FOR PARAMETRIZED ELLIPTIC ADVECTION-REACTION PROBLEMS

In this work we consider the Reduced Basis method for the solution of parametrized advection-reaction partial differential equations. For the generation of the basis we adopt a stabilized finite element method and we define the Reduced Basis method in the ＂primal- dual＂ formulation for this stabilized problem. We provide a priori Reduced Basis error estimates and we discuss the effects of the finite element approximation on the Reduced Basis error. We propose an adaptive algorithm, based on the a posteriori Reduced Basis error estimate, for the selection of the sample sets upon which the basis are built; the idea leading this algorithm is the minimization of the computational costs associated with the solution of the Reduced Basis problem. Numerical tests demonstrate the efficiency, in terms of computational costs, of the ＂primal-dual＂ Reduced Basis approach with respect to an ＂only primal＂ one. Parametrized advection-reaction partial differential equations, Reduced Basis method, ＂primal-dual＂ reduced basis approach, Stabilized finite element method, a posteriori error estimation.

A Static Condensation Reduced Basis Element Approach for the Reynolds Lubrication Equation

In this paper,we propose a Static Condensation Reduced Basis Element(SCRBE)approach for the Reynolds Lubrication Equation(RLE).The SCRBEmethod is a computational tool that allows to efficiently analyze parametrized structures which can be decomposed into a large number of similar components.Here,we extend the methodology to allow for a more general domain decomposition,a typical example being a checkerboard-pattern assembled from similar components.To this end,we extend the formulation and associated a posteriori error bound procedure.Our motivation comes from the analysis of the pressure distribution in plain journal bearings governed by the RLE.However,the SCRBE approach presented is not limited to bearings and the RLE,but directly extends to other component-based systems.We show numerical results for plain bearings to demonstrate the validity of the proposed approach.