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Dynamic Modeling of the Feed Drive System of a CNC Metal Cutting Machine

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Sound & Vibration 2021年第1期55卷 19-30页

作者： h.heydarnia I.A.Kiselev M.M.Ermolaev S.Nikolaev Department of Applied Mechanics Bauman Moscow State Technical UniversityMoscowRussia Department of Bases of Machine Designing Bauman Moscow State Technical UniversityMoscowRussia Skolkovo Institute of Science and Technology MoscowRussia

Studying the vibrational behavior of feed drive systems is important for enhancing the structural performance of computer numerical control(CNC)*** preload on the screw and nut position have a great influence on the vibration characteristics of the feed drive as two very important operational *** acceleration of the screw also affects the performance of the CNC feed drive when machining small *** paper investigates the influence of preload and nut position on the vibration characteristics of the feed drive system of a CNC metal cutting machine in order to be able to eliminate an observed resonance occurred at high rotational speeds of the screw,corresponding to high feed ***,rational structural parameters of the feed drive system are selected in order to increase the rotational acceleration for improving the performance of the CNC *** and analyses showed that by selecting specific parameters of feed drive system and simultaneously applying a certain value of preload,a 97%increase in rotational acceleration and 30%time reduction considering the vibration resistance at high rotational speeds can be achieved.

关键词： Machining performance CNC machine tools vibration characteristics machine tool dynamic modeling

Current and future pharmacological therapies for managing cirrhosis and its complications

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World Journal of Gastroenterology 2019年第8期25卷 888-908页

作者： David Kockerling Rooshi Nathwani Roberta Forlano Pinelopi Manousou Benjamin h Mullish Ameet Dhar Liver Unit/Division of Integrative Systems Medicine and Digestive Disease Imperial College London

Due to the restrictions of liver transplantation,complication-guided pharmacological therapy has become the mainstay of long-term management of *** article aims to provide a complete overview of pharmacotherapy options that may be commenced in the outpatient setting which are available for managing cirrhosis and its complications,together with discussion of current controversies and potential future ***/Medline/Cochrane Library were electronically searched up to December 2018 to identify studies evaluating safety,efficacy and therapeutic mechanisms of pharmacological agents in cirrhotic adults and animal models of ***-selective betablockers effectively reduce variceal re-bleeding risk in cirrhotic patients with moderate/large varices,but appear ineffective for primary prevention of variceal development and may compromise renal function and haemodynamic stability in advanced *** observational studies suggest protective,haemodynamically-independent effects of beta-blockers relating to reduced bacterial *** gut-selective antibiotic rifaximin is effective for secondary prophylaxis of hepatic encephalopathy;recent small trials also indicate its potential superiority to norfloxacin for secondary prevention of spontaneous bacterial *** remain the mainstay of uncomplicated ascites treatment,and early trials suggest alpha-adrenergic receptor agonists may improve diuretic response in refractory *** have not demonstrated clinical effectiveness in treating refractory ascites and may cause detrimental *** initial hepatotoxicity concerns,safety of statin administration has been demonstrated in compensated ***,statins are suggested to have protective effects upon fibrosis progression,decompensation and *** as to whether proton pump inhibitors cause gut-liver-brain axis dysfunction is *** evidence indicates that anticoa

关键词： Cirrhosis Beta-blockers Rifaximin Diuretics Statins Proton pump inhibitors Pharmacology

Natural ray-emitting radionuclides in Egyptian cement

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Nuclear Science and Techniques 2005年第6期16卷 376-380页

作者： A.M.EL-ARABI A.ABBADY A.h. EL-KAMEL A. NOSIER A. MOUSTAFA Physics Deptartment Faculty of Science Qena South Valley University Egypt Physics Deptartment Faculty of Science Assiut University Egypt Physics Deptartment Faculty of Science El-Azhar University Egypt

Samples of cement manufactured in Egypt and the raw materials have been analyzed usinggamma-spectroscopy, in order to determine the concentration of natural radionuclides and associated radiologicalhazard. The mean of specific activity due to radionuclides of 226 Ra, 232 Th and 40 K was found to be (20±4), (11± 2),(320±18) (gypsum), (41±8), (27±5), (410±27) (clay), (58±11), (18±3), (321±20) (iron ore) and (37.6±6), (11.8±3),(178.6±15) Bq?kg -1 (Portland cement), respectively. 40 K concentration could not be detected in slag, limestone, sul-phateresistant cement (S.R.C.), clinker and white cement, while the mean specific activities of 226 Ra and 232 Th are(239±16), (48.7±7); (31.5±5), (10±2); (47±7), (20±5); (23±5), (10.4±3) and (23±5), (11±3) Bq?kg -1 , respectively. Theactivities (concentrations) are in the same range as the data released in other countries. The calculated radiation haz-ardparameters for all the samples are still lower than the acceptable values in Egypt and other countries.

关键词： γ射线放射性核埃及伽马射线

Bending,buckling and vibration analyses of MSGT microcomposite circular-annular sandwich plate under hydro-thermo-magneto-mechanical loadings using DQM

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International Journal of Smart and Nano Materials 2018年第4期9卷 233-260,I0002页

作者： M.Mohammadimehr M.Emdadi h.Afshari B.Rousta Navi Department of Solid Mechanics Faculty of Mechanical EngineeringUniversity of KashanKashanIran

The purpose of this paper is to investigate the bending,buckling,vibration analyses of microcomposite circular-annular sandwich plate with CNT reinforced composite facesheets under hydro-thermo-magneto-mechanical loadings are presented using first order shear deformation theory(FSDT)and modified strain gradient theory(MSGT)that includes three material length scale ***,an isotropic homogeneous core is considered for microcomposite circular-annular sandwich *** generalized rule of mixture is employed to predict mechanical,moisture and thermal properties ofmicrocomposite sandwich *** using hamilton’s principle,governing equations are solved by differential quadrature method(DQM)for a circular annular sandwich *** predicted results are validated by carrying out the comparison studies for the FGM plates by modified couple stress theory(MCST).The obtained results are given to indicate the influence of the material length scale parameter,core-to-facesheet thickness ratios,magnetic effect,thermal andmoisture effects on the dimensionless deflection,critical buckling load,and natural frequency of microcomposite circular sandwich *** results can be employed in solid-state physics,materials science,nano-electronics,and nano electro-mechanical devices such as microactuators,and microsensor.

关键词： Bending buckling free vibration analyses circular annular sandwich plate CNT reinforced composite facesheets first order shear deformation and modified strain gradient theories

Evaluation of computer imaging technique for predicting the SPAD readings in potato leaves

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Information Processing in Agriculture 2017年第4期4卷 275-282页

作者： M.S.Borhan S.Panigrahi M.A.Satter h.Gu Research Specialist Agricultural and Biosystems Engineering DepartmentNorth Dakota State UniversityFargoND 58105USA Electrical and Computer Engineering Technology Purdue University West LafayetteIN 47907USA Agricultural and Biosystems Engineering Department North Dakota State UniversityFargoND 58105USA Graduate Student Computer Science DepartmentNorth Dakota State UniversityFargoND 58105USA Senior Software Developer Psychology DepartmentNorth Dakota State UniversityFargoND 58105USA

Facilitating non-contact measurement,a computer-imaging system was devised and evaluated to predict the chlorophyll content in potato leaves.A charge-coupled device(CCD)camera paired with two optical filters and light chamber was used to acquire green(550±40 nm)and red band(700±40 nm)images from the same *** leaves from 15 plants differing in coloration(green to yellow)and age were selected for this *** based image features,such as mean and variances of green and red band images,were extracted from the *** analyses demonstrated that the variations in SPAD meter reading could be explained by themeangrayandvariances of gray scale *** fitted least square models based on the mean gray scale levels were inversely related to the chlorophyll content of the potato leaf with a R^2 of 0.87 using a green band image and with an R2 of 0.79 using a red band *** the extracted four image features,the developed multiple linear regression model predicted the chlorophyll content with a high R^2 of 0.88).The multiple regression model(using all features)provided an average prediction accuracy of 85.08% and amaximum accuracy of 99.8%.The prediction model using only mean gray value of red band showed an average accuracy of 81.6% with a maximum accuracy of 99.14%.

关键词： Computer imaging Chlorophyll SPAD meter Regression Prediction accuracy

Use of omental patch and endoscopic closure technique as an alternative to surgery after endoscopic full thickness resection of gastric intestinal stromal tumors: A series of cases

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World Journal of Clinical Cases 2020年第1期8卷 120-125页

作者： Amit h Sachdev Shahzad Iqbal Igor Braga Ribeiro Diogo Turiani hourneaux de Moura Division of Gastroenterology Hepatology and EndoscopyBrigham and Women’s HospitalHarvard Medical SchoolBostonMA 02115United States Good Samaritan hospital NY 11795United States Gastrointestinal Endoscopy Unit Hospital das Clínicas da Faculdade de Medicina da Universidade de São PauloSão Paulo 05403-000Brazil

BACKGROUND Gastrointestinal stromal tumors(GISTs)originate from interstitial cells of *** can occur anywhere along the gastrointestinal *** lesions have traditionally been removed ***,with recent innovations in advanced endoscopy,GISTs located within the stomach are now removed *** describe a new innovative endoscopic technique to close large and hard to access defects after endoscopic full-thickness resection of gastric *** SUMMARY We present a series of three patients who were diagnosed with a gastric *** patients underwent full-thickness endoscopic *** all cases,for closure of the surgical bed,conventional endoscopic techniques including hemoclips,endoloop and suturing were *** performed a new technique in which we pulled omental fat into the gastric lumen and completely closed the defect using endoscopic *** patients performed well post-procedure and computed tomography was carried out one day after the procedures which showed no extravasation of *** The omental plug technique may be used as an alternative to surgery in selected cases of gastric perforation.

关键词： Gastric perforation Gastrointestinal stromal tumors Gastric tumor Surgery Endoscopy Suturing

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A new microchannel capillary flow assay (MCFA) platform with lyophilized chemiluminescence reagents for a smartphone-based POCT detecting malaria

作者： (苏)M.h雷季娜等

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Microsystems & Nanoengineering 2020年第1期6卷 1316-1333页

作者： Sthitodhi Ghosh Kashish Aggarwal Vinitha T.U Thinh Nguyen Jungyoup han Chong h.Ahn Department of Electrical Engineering and Computer Science Microsystems and BioMEMS LaboratoryUniversity of CincinnatiCincinnatiOH 45221USA Mico BioMed USA Inc. 10999 Reed Hartman HighwaySTE 309CCincinnatiOH 45242USA

There has been a considerable development in microfluidic based immunodiagnostics over the past few years which has greatly favored the growth of novel point-of-care-testing(POCT).however,the realization of an inexpensive,low-power POCT needs cheap and disposable microfluidic devices that can perform autonomously with minimum user *** work,for the first time,reports the development of a new microchannel capillary flow assay(MCFA)platform that can perform chemiluminescence based ELISA with lyophilized chemiluminescent *** new MCFA platform exploits the ultra-high sensitivity of chemiluminescent detection while eliminating the shortcomings associated with liquid reagent handling,control of assay sequence and user *** functionally designed microchannels along with adequate hydrophilicity produce a sequential flow of assay reagents and autonomously performs the ultra-high sensitive chemiluminescence based ELISA for the detection of malaria biomarker such as *** MCFA platform with no external flow control and simple chemiluminescence detection can easily communicate with smartphone via USB-OTG port using a custom-designed optical *** use of the smartphone for display,data transfer,storage and analysis,as well as the source of power allows the development of a smartphone based POCT analyzer for disease *** paper reports a limit of detection(LOD)of 8 ng/mL by the smartphone analyzer which is sensitive enough to detect active malarial *** MCFA platform developed with the smartphone analyzer can be easily customized for different biomarkers,so a hand-held POCT for various infectious diseases can be envisaged with full networking capability at low cost.

关键词： POCT smart capillary