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Investigation of a dynamics-oriented engineering approach to ultraprecision machining of freeform surfaces and its implementation perspectives

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Nanotechnology and Precision Engineering 2021年第4期4卷 12-23页

作者： ali khaghani Kai Cheng Department of Mechanical and Aerospace Engineering(MAE) Brunel University LondonKingston LaneUxbridge UB83PHUnited Kingdom

In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary ***,positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are *** ultraprecision machining of freeform surfaces using slow tool servo mode in particular,however,account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece *** important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application *** this paper,an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo *** approach is focused on seamless integration of multibody dynamics,cutting forces,and machining dynamics,while targeting the positioning and control of the tool–workpiece loop in the machining *** positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece *** interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining *** approach is illustrated using a virtual machining system developed and supported with simulations and experimental ***,the paper provides further explorations and discussion on implementation perspectives of the approach,in combination with case studies,as well as discussing its fundamental and industrial implications.

关键词： Ultraprecision machining Freeform surface Dynamics-oriented approach Dynamic cutting force Slow tool servo mode Microcutting

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CFD-based design and analysis of air-bearing-supported paint spray spindle

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Nanotechnology and Precision Engineering 2018年第4期1卷 226-235页

作者： ali khaghani Kai Cheng College of Engineering Design and Physical Sciences Brunel University London

In this paper, an analytical scientific approach is presented for the design and analysis of an air-turbine-driven paint spray spindle, and it is used to improve further the design concept of the existing spindle applied in automotive coating and paint spraying applications. The current spindle on the market can operate at a maximum speed of 100,000 rpm and features a maximum bell size of 70 mm diameter. Given the increasing demands for high automotive coating/painting quality and productivity in assembly, the design and development of a paint spray spindle with a speed of 145,000 rpm or higher is needed. Computational fluid dynamics(CFD)-based simulation is applied in the approach. Accordingly, CFD simulation-based design and analysis are undertaken, covering the characteristic factors of velocity, pressure of the air supply, rotational speed of the air-turbine, and torque and force reaction on the turbine blades. Furthermore, the turbine blade geometric shape is investigated through the simulations. Three geometrical concepts have been investigated against the original model. The results on Concept_03 verified the higher angular velocity speeds against the theoretical model. The pressure and velocity effects in the blades have been investigated. The results show that the pressure and velocity of the air supply driving the turbine are critical factors influencing the stability of turbine spinning. The results also demonstrate that the force acting on the blades is at the highest level when the adjacent face changes from a straight surface into a curve. Finally, changing the geometrical shape in the turbine likely increases the tangential air pressure at the blades surface and relatively increases the magnitude of the lateral torque and force in the spindle. Notwithstanding this condition, the analytical values surpass the theoretical target values.

关键词： Air-bearing CFD analysis Paint spray spindle Air-turbine design Turbine blade design and optimization

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The emergence of drug resistant HIV variants and novel anti-retroviral therapy

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Asian Pacific Journal of Tropical Biomedicine 2013年第7期3卷 515-522页

作者： Koosha Paydary Parisa khaghani Sahra Emamzadeh-Fard Seyed Ahmad Seyed alinaghi Kazem Baesi Iranian Research Center for HIV/AIDS (IRCHA) Iranian Institute for Reduction of High-Risk Behaviors Tehran University of Medical SciencesTehran Iran Students'Scientific Research Center Tehran University of Medical SciencesTehran Iran

After its identification in 1980s,HIV has infected more than 30 million people *** era of highly active anti-retroviral therapy,anti-retroviral drug resistance results frominsufficient anti-retroviral pressure,which may lead to treatment *** studiessupport the idea that anti-retroviral drug resistance has evolved largely as a result of low-adherence of patients to therapy and extensive use of anti-retroviral drugs in the developedworld;however,a highly heterogeneous horde of viral quasi-species are currently circulating indeveloping ***,the prioritizing of strategies adopted in such two worlds should be quitedifferent considering the varying anti-retroviral drug resistance *** this article,weexplore differences in anti-retroviral drug resistance patterns between developed and developingcountries,as they represent two distinct ecological niches of HIV from an evolutionary standpoint.

关键词： HIV infection Evolution,Drug resistance Developed world Developing world

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Effect of Network Traffic on IPS Performance

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Journal of Information Security 2012年第2期3卷 162-168页

作者： Shahriar Mohammadi Vahid Allahvakil Mojtaba khaghani Department of IT Khajeh Nasir University Tehran Iran

The importance of network security has grown tremendously and intrusion prevention/detection systems (IPS/IDS) have been widely developed to insure the security of network against suspicious threat. Computer network intrusion detection and prevention system consist of collecting traffic data, analyzing them based on detection rules and generate alerts or dropping them if necessary. However IPS has problems such as accuracy signature, the traffic volume, topology design, monitoring sensors. In this paper, we practically examine the traffic effect on performance of IPS. We first examine the detection of DOS attack on a web server by IPS and then we generate network traffic to see how the behavior of IPS has influenced on detection of DOS attack.

关键词： Network Security Network Intrusion Detection and Prevention System DOS Attack Network Traffic Generation

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X-ray spectroscopy evidence for plasma shell formation in experiments modeling accretion columns in young stars

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Matter and Radiation at Extremes 2019年第6期4卷 22-29页

作者： E.D.Filippov I.Yu.Skobelev G.Revet S.N.Chen B.Khiar A.Ciardi D.khaghani D.P.Higginson S.A.Pikuz J.Fuchs Joint Institute for High Temperatures RAS125412 MoscowRussia National Research Nuclear University “MEPHI”115409 MoscowRussia LULI-CNRS ´Ecole PolytechniqueCEA:Universit´e Paris-SaclayUPMC Univ Paris 06:Sorbonne Universit´eF-91128 Palaiseau CedexFrance ELI-NP “Horia Hulubei”National Institute for Physics and Nuclear Engineering30 Reactorului StreetRO-077125 Bucharest-MagureleRomania Sorbonne Universit´e Observatoire de ParisUniversit´e PSLCNRSLERMAF-75005 ParisFrance Flash Center for Computational Science University of Chicago5640 S.Ellis AvenueChicagoIllinois 60637USA University of Bordeaux CEACNRSCentre Lasers Intenses et ApplicationsUMR 510733405 Talence CedexFrance Lawrence Livermore National Laboratory LivermoreCalifornia 94551USA

Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star *** particular,we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on young stars[*** et al.,***.3,e1700982(2017)].The present paper focuses on x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics involved in such *** demonstrate that we can infer the formation of a plasma shell,surrounding the accretion column at the location of impact with the stellar surface,and thus resolve the present discrepancies between mass accretion rates derived from x-ray and optical-radiation astronomical observations originating from the same *** our experiments,the accretion column ismodeled by having a collimated narrow(1 mm diameter)plasma stream first propagate along the lines of a large-scale external magnetic field and then impact onto an obstacle,mimicking the high-density region of the stellar chromosphere.A combined approach using steady-state and quasi-stationarymodels was successfully applied tomeasure the parameters of the plasma all along its propagation,at the impact site,and in the structure surrounding the impact *** formation of a hot plasma shell,surrounding the denser and colder core,formed by the incoming stream of matter is observed near the obstacle using x-ray spatially resolved spectroscopy.

关键词： accretion stars stellar

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Selective Cytotoxicity and Apoptogenic Activity of Hibiscus Sabdariffa Aqueous Extract Against MCF-7 Human Breast Cancer Cell Line

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Journal of Cancer Therapy 2011年第3期2卷 394-400页

作者： Shahnaz khaghani Farideh Razi Mohsen Mohammadian Yajloo Malihe Paknejad Ahmad Shariftabrizi Parvin Pasalar 不详

Background: Herbal compounds are attractive anticancer candidates due to their low toxicity. Pervious studies have demonstrated that Hibiscus sabdariffa is promising as an anticancer agent against several cancer types;however, its potential therapeutic role in breast cancer remains to be investigated. Materials and Methods: In the present study, the cytotoxic effects of Hibiscus sabdariffa aqueous extract (HSE) on a human breast adenocarcinoma cell line (MCF-7) and fetal foreskin fibroblast (HFFF) were investigated. Different concentrations of water extract of calyces were added and the percentage of cell survival was determined after 24, 48, and 72 hours using an MTT assay. Apoptosis induction was assessed by DNA fragmentation. Results: At the concentration of 0.5 mg/ml of the extract and following 72 hours of incubation, the number of viable MCF-7 cells was less than 50%. The extract was not cytotoxic against normal HFFF cells in all tested concentrations. Also, HSE induced apoptosis only in MCF-7 cells. Conclusions: These results suggest that HSE inhibits the growth of MCF-7 cells selectively in a concentration- and time-dependent manner. As this herbal substance has been shown to be nontoxic at very high doses in experimental animals, it might be a good anticancer drug candidate for breast cancer treatment.

关键词： Hibiscus Sabdariffa Natural Anticancer Compound MTT Assay Apoptosis Breast Cancer

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