جستجوی مقالات مرتبط با کلیدواژه « law of conservation of momentum » در نشریات گروه « مکانیک »
تکرار جستجوی کلیدواژه « law of conservation of momentum » در نشریات گروه « فنی و مهندسی »-
جمعیت رو به افزایش جهان، تغییر سبک زندگی و شمار محدود منابع طبیعی و انرژی همگی سبب شده است که تاسیسات صنعتی آب شیرین کن، مدعیان اصلی تولید بصرفه آب شیرین باشند. در این پژوهش، تلفیق نیروگاه سیکل ترکیبی (CCPP) با تاسیسات تقطیر با تاثیر چندگانه (MED) و آب شیرین کن به روش اسمز معکوس (RO) از طریق تحلیل های جامع عادی و پیشرفته اگزرژی، اگزرژی-اقتصادی و اگزرژی-زیست محیطی بررسی می شود. در ابتدا، مدلسازی ترمودینامیک CCPP با استفاده از شیوه برنامه نویسی ریاضیاتی انجام می شود. سپس، برای تلفیق CCPP موجود با تاسیسات MED و آب شیرین کن RO، مدلی ریاضیاتی ارایه می شود. در انتها، تحلیل های عادی و پیشرفته فوق الذکر به منظور ارزیابی پارامترهای عملکردی اصلی سیستم یکپارچه CCPP و آب شیرین کن MED-RO، و شناسایی پیشرفت های بالقوه فنی، اقتصادی و زیست محیطی صورت می گیرد. مطالعه ای موردی نیز در مورد نیروگاه برق شهید سلیمی نکا واقع در شمال ایران در راستای دریای خزر ارایه می شود. روش مدلسازی ریاضیاتی برای این سیستم یکپارچه در برنامه «متلب» حل می شود و نتایج آن ازطریق نرم افزار «ترموفلکس» اعتبارسنجی می شوند. نتایج نشان از افزایش 3.79٪ مصرف سوخت پس از تلفیق CCPP و تاسیسات آب شیرین کن دارند. بازدهی اگزرژی سیستم پیشرفته 42.7 درصد و بالاترین هزینه تخریب اگزرژی محفظه احتراق 1.09 دلار در هر ثانیه است. تحلیل های اقتصادی و زیست محیطی سیستم یکپارچه همچنین نشان می دهد که توربین های گازی بالاترین هزینه سرمایه گذاری (0.047 دلار در هر ثانیه) را دارند. در عین حال، سیستم MED بیشترین نرخ پیامد زیست محیطی، یعنی 0.025 نقطه در ثانیه، را داراست.
کلید واژگان: مدلسازی ریاضیاتی و شبیه سازی, آب شیرین کن, آب و تولید برق, نیروگاه سیکل ترکیبی (CCPP), تقطیر با تاثیر چندگانه (MED), اسمز معکوس (RO), تحلیل اگزرژی پیشرفته, تحلیل اگررژی-اقتصادی, تحلیل اگزرژی-زیست محیطی}The increasing population of the world, the change of style and the limited number of natural resources and energy all make freshwater industrial productions the main contenders for the cost-effective production of freshwater. In this research, the combination of combined cycle power plant (CCPP) using multiple effect distillation (MED) and reverse osmosis (RO) desiccation techniques is investigated through normal and advanced exergy, exergy-economic and exergy-environmental comprehensive analysis. First, CCPP thermodynamic modeling is done using mathematical programming method. Then, a mathematical model is presented to integrate the existing CCPP with MED and RO desalination plants. Finally, the aforementioned normal and advanced analyzes are performed to evaluate the main performance parameters of the integrated CCPP system and MED-RO desalination system, and to identify potential technical, economic, and environmental improvements. A case study is also presented about the Shahid Salimi Neka power plant located in the north of Iran along the Caspian Sea.The mathematical modeling method for this integrated system is solved in "MATLAB" program and its results are validated by "Thermoflex" software. The results show a 3.79% increase in fuel consumption after combining CCPP and water desalination facilities. The exergy efficiency of the advanced system is 42.7% and the highest combustion chamber exergy destruction cost is $1.09 per second. Economic and environmental analyzes of the integrated system also show that gas turbines have the highest investment cost ($0.047 per second). At the same time, the MED system has the highest environmental impact rate, i.e. 0.025 points per second.
Keywords: mathematical modeling, simulation, Desalination, Water, power generation, combined cycle power plant (CCPP), Multiple Effect Distillation (MED), reverse osmosis (RO), Advanced exergy analysis, Agro-economic analysis, Exergy-environmental analysis} -
This paper considers the context of renewable energy generation for a photo voltaic solar generating system with a non-linear load using one cycle controller with a motor across terminals. The paper finds a comparative study of the pulse width modulator with one cycle controller, which analyses both concepts using power sim software. The main challenge is to reject power supply disturbance. The frequency switch controls the single constant cycle and regulates direct current supply but with transients. As in the case of pulse width modulation, transients appear. In comparison, the one-cycle controlling technique rejects power supply disturbance as the constant voltage maximum power point tracker returns a reference speed value with the speed sensor, so one switching cycle is combined with a dual compensator to reject power supply disturbance as photo voltaic solar generation resolves the supply disturbance in a closed-loop scheme using one cycle modulator. So, in the case of the pulse width modulation technique, the ideal efficiency using the pulse width modulation controller varies from 70.45 % to 75 %; in the case of the novel one-cycle control modulator's excellent efficiency varies from 95.17 % to 99.49 %. Since switching converters efficiently control the photo voltaic energy generation system using one cycle control modulator rather than a pulse width modulator, apart from the swift transient response, one-cycle control modulator imparts economically efficient reference tracking and robustness to the system. The outcome of the one-cycle controller and pulse width modulated controller validates the analysis of variance (ANOVA).Keywords: Proportional Integrator (PI), DC to DC Buck, Boost, DC to DC Boost Converter, Maximum power point tracking (MPPT), Pulse Width Modulation (PWM)}
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This paper presents an analytical solution for stability analysis of thick rectangular functionally graded plates with porosity subjected to in-plane loadings using the higher-order shear and normal deformation plate theory, for the first time. The plate material and its porosity are assumed to vary along the thickness direction. Also, three types of porosity pattern along the thickness are considered. Since the plate structure is not generally symmetry to the mid-plane it is assumed that the in-plane loads are applied to its neutral plane to remove the bending-stretching coupling. Stability equations are derived and then analytically solved for rectangular plates with simple supports using Legendre orthonormal polynomials and Navier’s method to determine the critical buckling load. The results are then compared with estimates made using higher-order shear deformation (HSDT) and classical plate theories (CPT) available in the literature for FG non-porous plates. It is shown that compared to the HSDT, the HOSNDT yields smaller values for the plate critical buckling load and the effect of HSNDT is more important as the plate thickness increases. In addition, it is demonstrated that compared to the uniaxial load, the effect of HSNDT is greater as the plate is subjected to a biaxial compression load. Finally, the effects of the porosity distribution, porosity, power-law index, loading condition, and thickness ratio are studied in detail using HOSNDT. The results show that the porosity effect is greater in smaller values of the power law index parameter.Keywords: Higher order shear, normal deformations plate theory, Functionally graded porous materials, Thick rectangular plates, Legendre orthonormal polynomials, stability analysis, Porosity effect}
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روش مناسب برای اتصال پلیمرهای تقویت شده با الیاف کربن (CFRP) به آلومینیوم که باعث توزیع تنش یکنواخت، عملکرد خستگی مناسب تر و کاهش وزن می گردد اتصال چسبی می باشد. در اتصال چسبی سطح تماس چسبنده ها و چسب نواحی حساس برای شروع و گسترش خرابی می باشند. برای از بین بردن آلودگی های سطحی چسبنده ها بایستی عملیات سطحی شوند. در این تحقیق تاثیر الگوی هدفمند عملیات سطحی لیزری در استحکام اتصال چسبی کامپوزیت/آلومینیوم مود اول شکست مورد بررسی قرار گرفته است. ابتدا عملیات سطحی لیزری در سرتاسر نمونه ها انجام شده تا بتوان پارامترهای دستگاه لیزر که با ایجاد کیفیت سطح مناسب باعث افزایش استحکام اتصال می گردند پیدا شوند. سپس الگوی سطح هدفمند لیزری با پارامترهای مناسب برای ایجاد سایش و تمیزکاری سطح چسبنده ها انجام شده است. نتایج نشان دهنده افزایش 5/15% نرخ رهایی انرژی کرنشی بحرانی مود اول برای نمونه عملیات سطحی لیزری سرتاسری نسبت به روش سنباده زنی می باشد. این در حالی است که با الگوی هدفمند عملیات سطحی لیزری نرخ رهای انرژی کرنشی بحرانی مود اول بترتیب 9/5% و 4/22% نسبت به عملیات سطحی لیزری سرتاسری و سنباده زنی افزایش پیدا کرده است. بررسی سطح شکست نمونه ها نشان دهنده به تاخیر افتادن رشد ترک در نمونه های الگوی هدفمند عملیات سطحی لیزری با تغییر از حالت خرابی اتصال به پارگی الیاف می باشد که باعث بهبود استحکام اتصال شده است.
کلید واژگان: اتصال چسبی, پلیمرهای تقویت شده با الیاف کربن, الگوی هدفمند عملیات سطحی لیزری, نمونه تیریکسرگیردار دولبه, نرخ رهایی انرژی کرنشی بحرانی مود اول شکست}The proper method for jointing Carbon fiber reinforced polymers (CFRP) to aluminum, which causes uniform stress distribution, more suitable fatigue performance and weight reduction, is adhesive bonded joint. In adhesive bonding, the interface of adhesives and adherent are sensitive areas for the initiation and propagation of failure. In order to eliminate surface contamination, adherents must be surface treated. In this research, the effect of the functional pattern of laser surface treatment on the strength of aluminum/composite adhesive bonded joint in the mode I fracture has been investigated. At first, laser surface treatments were performed throughout the specimen in order to find the parameters of the laser device that increase the strength of the adhesive bonding by creating a suitable surface quality. After that, the functional pattern of laser surface treatment with the appropriate parameters for ablation and cleaning of the adhesive surface is done. The results show a 15.5% increase in the critical strain energy release rate of the mode I for the all-over laser surface treatment specimen compared to the sanding method. Meanwhile, with the functional pattern of laser surface treatment, the critical strain energy release rate of the mode I has increased by 5.9% and 22.4% compared to all-over laser surface treatment and sanding, respectively. Examining the fracture surface of the specimen shows the delay in crack growth in the specimen of the functional pattern with changes from the adhesive failure to the fiber tearing, which has improved the strength of the adhesive bonding.
Keywords: Adhesive bonded joint, Carbon fiber reinforced polymers, Functional pattern of laser surface treatment, Double-cantilever beam specimen, critical strain energy release rate of the mode I fracture} -
This article applies the variational Kantorovich-Vlasov method to obtain exact mathematical solutions to the bending problem of thin plate with two opposite simply supported edges and two free edges. Vlasov method was adopted simultaneously in the variational Kantorovich method, and the deflection function w(x, y) is expressed in variable-separable form as single infinite series in terms of the unknown function g(y) and known sinusoidal functions of x coordinate variable f(x) where f(x) satisfies Dirichlet boundary conditions at the simple supports. The total potential energy functional , expressed in terms of g(y) and the derivatives g(y), g(y) is then minimized with respect to g(y) using the Euler-Lagrange differential equations. The resulting equation of equilibrium is a fourth order inhomogeneous ordinary differential equation (ODE) in g(y). The general solution is found and boundary conditions are enforced to find the integration constants. The expression found for w(x, y) satisfies the governing equations on the domain and the boundaries and is thus exact within the scope of thin plate theory adopted to idealize the plate. Moment-deflection equations are used to obtain exact analytical expressions for the bending moments Mxx, Myy. Deflection and bending moments are computed at the plate center; as well as at the middle of the free edges. Comparison of the plate center deflections and bending moments for various aspect ratios illustrate that the exact solutions by the present work are in the agreement with Levy solutions presented by Timoshenko and Woinnowsky-Krieger and symplectic elasticity solutions presented by Cui Shuang. The present results for bending moments at the free edges for various aspect ratios agree with the Levy results presented by Timoshenko and Woinowsky-Krieger and symplectic elasticity results presented by Cui Shuang.Keywords: Variational Kantorovich-Vlasov method, total potential energy functional, Deflection, Bending moment, Euler-Lagrange differential equation, ordinary differential equation, Kirchhoff Plate Theory}
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مدیریت ترافیک فضایی، راهی برای توسعه پایدار و طولانی مدت از فضای ماورای جو با رویکرد کاهش برخورد اجسام است. در این مقاله ارزیابی ریسک برخورد ماهواره ها با استفاده از روش احتمال برخورد انجام می شود. از میان روش های مختلف تعیین احتمال برخورد، روش پاترا (2005) و روش چان برای تعیین احتمال برخورد ماهواره نور با سایر اجسام فضایی استفاده شده است. نرم افزارهای مختلفی برای شبیه سازی حرکت و محاسبه احتمال برخورد اجسام در فضا توسعه داده شده اند. با توجه به معیارهایی که در متن اصلی شرح داده شده است، از ابزار Advanced Conjunction Analysis نرم افزار STK برای تحلیل ریسک برخورد ماهخواره ملی نور با سایر اجسام فضایی استفاده می شود. در این نرم افزار با استفاده از داده دو سطری اجسام فضایی و انتخاب مدل انتشار مداری، موقعیت هر جسم در فضا مشخص می شود. سپس با یکی از روش های تخمین احتمال، احتمال برخورد تعیین می شود. براساس احتمال به دست آمده میتوان در خصوص لزوم مانور ماهواره در زمان مناسب تصمیمگیری نمود.کلید واژگان: مدیریت ترافیک فضایی, المان دوسطری, اجتناب از برخورد, مدل های محاسبه احتمال برخورد, روش پاترا, تعیین مدار, کوواریانس خطا, نرم افزار STK}In this article collision probability method is used to satellite collision risk analysis. Among different methods introduced for determining collision probability, Patera's (2005) and Chan methods are chosen to define Noor satellite collision to the other space objects. According to criteria described in the article, Advanced Conjunction Analysis Tools of STK software applied for collision risk analysis. The software, determine position of each object in space using Two Line Elements and appropriate propagation model according to altitude of the orbit. So collision probability calculated by one of the cpllision probability methods. If derived prababilty is larger than 10-3, so its necessary to schdule for suitable maneuver to avoid collision.Keywords: Space Traffic Management, Two Line Element, Collision Avoidance, Collision Probability Calculation Models, Patera Method, Orbit Determination, Error Covariance, STK software}
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This paper is the second part of a two-part research work intended at realizing a systematic computational and experimental analysis of the principal data-driven identification procedures based on the Observer/Kalman Filter Identification Methods (OKID) and the Numerical Algorithms for Subspace State-Space System Identification (N4SID). More specifically, this second paper treats the presentation of the numerical analysis and the experimental testing carried out in this study. To perform a systematic comparison, the identification methods mentioned before are implemented in a general-purpose computer program developed in the MATLAB computational environment. To this end, a simple two-degrees-of-freedom dynamical model of a vibrating mechanical system is considered first as a demonstrative example. The demonstrative example is used to carry out a numerical analysis of the performance of the computational methods of interest for this investigation. Subsequently, an experimental analysis is carried out focusing on a three-dimensional structure that vibrates under the effect of an external source of impulsive excitation. To perform a thorough analysis, the flexible structure employed as an experimental case study is modeled starting from its CAD geometric model and assuming different levels of complexity, which range from a simple three-degrees-of-freedom lumped parameter model to a relatively more complex linear finite element model. In the paper, the mechanical models of the structural system considered as illustrative examples are principally employed for comparing the results arising from the modal analysis. The computational and experimental analysis of these structural models turned out to be useful to trace guidelines for evaluating the effectiveness and the efficiency of the numerical and experimental results obtained from the identification process. In this study, a numerical and experimental analysis of the OKID algorithms and the N4SID methods is developed. Both classes of techniques enable the time-domain state-space system identification, that is, they construct an estimation of the state, input influence, output influence, and direct transmission matrices which characterize the dynamic properties of a mechanical system. The present investigation demonstrates that, if properly tuned, both the OKID methods and the N4SID algorithms lead to consistent numerical and experimental results, even in the case when the input-output measurements used for performing the identification procedure are affected by a certain degree of noise. The numerical and experimental results found in this second part of the research work confirmed the efficacy of the time-domain system identification methodologies described in the first part of the paper.Keywords: Applied System Identification, Experimental Modal Analysis, Observer, Kalman Filter Identification Methods (OKID), Numerical Algorithms for Subspace State-Space System Identification (N4SID), Mass, Stiffness, and Damping Matrices Identification (MKR)}
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This paper is the first part of a two-part research work aimed at performing a systematic computational and experimental analysis of the principal data-driven identification procedures based on the Observer/Kalman Filter Identification Methods (OKID) and the Numerical Algorithms for Subspace State-Space System Identification (N4SID). Considering the approach proposed in this work, the state-space model of a mechanical system can be identified with the OKID and N4SID methods. Additionally, the second-order configuration-space dynamical model of the mechanical system of interest can be estimated with the MKR (Mass, Stiffness, and Damping matrices) and PDC (Proportional Damping Coefficients) techniques. In particular, this first paper concentrates on the description of the fundamental analytical methods and computational algorithms employed in this study. In this investigation, numerical and experimental analyses of two fundamental time-domain system identification techniques are performed. To this end, the main variants of the OKID and the N4SID methods are examined in this study. These two families of numerical methods allow for identifying a first-order state-space model of a given dynamical system by directly starting from the time-domain experimental data measured in input and output to the system of interest. The basic steps of the system identification numerical procedures mentioned before are described in detail in the paper. As discussed in the manuscript, from the identified first-order state-space dynamical models obtained using the OKID and N4SID methods, a second-order configuration-space mechanical model of the dynamic system under consideration can be subsequently obtained by employing another identification algorithm described in this work and referred to as the MKR method. Furthermore, by using the second-order dynamical model obtained from experimental data, and considering the hypothesis of proportional damping, an effective technique referred to as the PDC method is also introduced in this investigation to calculate an improved estimation of the identified damping coefficients. In this investigation, a numerical and experimental comparison between the OKID methods and the N4SID algorithms is proposed. Both families of methodologies allow for performing the time-domain state-space system identification, namely, they lead to an estimation of the state, input influence, output influence, and direct transmission matrices that define the dynamic behavior of a mechanical system. Additionally, a least-square approach based on the PDC method is employed in this work for reconstructing an improved estimation of the damping matrix starting from a triplet of estimated mass, stiffness, and damping matrices of a linear dynamical system obtained using the MKR identification procedure. The mathematical background thoroughly analyzed in this first research work serves to pave the way for the applications presented and discussed in the second research paper.Keywords: Applied System Identification, Experimental Modal Analysis, Observer, Kalman Filter Identification Methods (OKID), Numerical Algorithms for Subspace State-Space System Identification (N4SID), Mass, Stiffness, and Damping Matrices Identification (MKR)}
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انرژی مورداستفاده جهت تامین سرمایش و گرمایش بخش قابل توجهی از انرژی مصرفی واحد صنعتی را شامل می شود. هدف اصلی در این مقاله بررسی عملکرد یک سیستم تولید سه گانه خورشیدی جهت تامین انرژی موردنیاز سیستم تهویه مطبوع یک واحد صنعتی است. سیستم پیشنهادی شامل یک چیلر جذبی لیتیوم بروماید آب دو اثره، پمپ حرارتی و کلکتورهای فتوولتاییک حرارتی دارای متمرکزکننده است. چیلر جذبی با ظرفیت و ضریب عملکرد اسمی به ترتیب 100 تن تبرید و 3/1 و پمپ حرارتی با ظرفیت 30 تن تبرید جهت پاسخگویی به نیاز سرمایشی ساختمان استفاده شده اند. سیستم خورشیدی شامل متمرکزکننده خورشیدی فرنل خطی، جاذب فتوولتاییک حرارتی دارای سلول سه لایه است. تحلیل برای مجموعه واقع در جنوب غربی تهران صورت پذیرفته است. شبیه سازی پویای سیستم با استفاده از نرم افزار ترنسیس و ای ای اس انجام گرفته است. در راستای مقایسه عملکرد کلکتور پیشنهادی، کلکتورهای فتوولتاییک حرارتی بدون متمرکزکننده و حرارتی دارای متمرکزکننده دارای سطح پوشش یکسان مورد بررسی قرار گرفته اند. انرژی تحویل شده کلکتور پیشنهادی به ترتیب 64 و 28 درصد بیشتر از کلکتورهای فتوولتاییک حرارتی بدون متمرکزکننده و حرارتی دارای متمرکزکننده است. ترکیب ساختار پیشنهادی در مقایسه با ساختاری که در آن از انرژی خورشیدی استفاده نمی شود به کاهش 62 درصدی مصرف انرژی می انجامد. استفاده از پمپ حرارتی در این ساختار موجب کاهش 58 درصدی انرژی مصرفی در مقایسه با عدم استفاده از آن می گردد. تولید انرژی الکتریکی توسط کلکتور پیشنهادی در سال 06/101 مگاوات ساعت است. سیستم پیشنهادی نیاز به گرمایش پشتیبان 07/264 مگاوات ساعت در سال برای رفع تمامی نیاز های تهویه مطبوع مجتمع دارد.
کلید واژگان: کلکتور فتوولتاییک حرارتی دارای متمرکزکننده, تولید سه گانه, تهویه مطبوع, تولید هم زمان برق و حرارت, سیستم انرژی, چیلر جذبی لیتیوم بروماید آب دو اثره}The energy used to provide cooling and heating is a significant part of the energy consumption of an industrial complex. This paper aims to evaluate the performance of a trigeneration solar-powered system to supply the air conditioning system of an industrial complex energy requirement. The proposed design includes a double-effect lithium bromide water absorption chiller, a heat pump, and concentrating photovoltaic-thermal solar collectors (CPVT). Absorption chillers with nominal capacity and coefficient of performance of 100 TR and 1.3, respectively, and a heat pump with a capacity of 30 TR have been used to meet the cooling demands. The solar system consists of linear Fresnel solar concentrators and triple-junction solar cells. The analysis has been conducted for the complex located southwest of Tehran, Iran. Dynamic system simulation is performed using TRNSYS and EES software. To compare the performance of the proposed collector, photovoltaic-thermal collectors without concentrators (PVT) and Thermal collectors with concentrators (CT) with the same coating surface have been investigated. The energy delivered by the proposed collector is 64% and 28% higher, respectively than the PVT and the CT collectors. Compared to a structure without solar energy utilization unit, the proposed design reduces energy consumption by 62%. Employment of the heat pump in this method reduces energy consumption by 58% compared system without it. The proposed collector electrical energy production in a year is 101.10 MWh. The proposed system needs 264.07 MWh of backup heating a year to meet all the complex air conditioning needs.
Keywords: concentrating photovoltaic, thermal collectors, multi-generation, air conditioning, co generation of power, heat, energy systems, lithium bromide water absorption chiller} -
In this paper, a new strategy for developing effective control policies suitable for guiding the motion of articulated mechanical systems that are described within the framework of multibody system dynamics is proposed. In particular, a scissor lift table having a pantograph topology is analytically modeled as a rigid multibody system by using a Lagrangian formulation. An operational approach is thus introduced in this investigation to design the control system that commands the motion of the lift table. In this vein, two dynamical models are developed in this investigation, namely a minimal coordinate multibody model and a redundant coordinate multibody model. While the minimal coordinate multibody model is used in the paper for the optimal design of a high-performing nonlinear controller, the redundant coordinate multibody model is employed to verify both the efficiency and the effectiveness of the control approach adopted in this work. More specifically, the nonlinear control system devised in this paper is based on the combination of an open-loop control architecture with a closed-loop control strategy. The open-loop control policy is determined by using a nonlinear quasi-static feedforward controller, whereas the closed-loop control action is obtained considering an error-based proportional-derivative feedback controller. With the use of both the pantograph scissor lift multibody models developed in this work, several numerical experiments are carried out in the paper, thereby demonstrating the readiness and the effectiveness of the control methodology proposed in this investigation.Keywords: Multibody System Modeling, Computational Kinematics, Statics, and Dynamics, Nonlinear Regulation, Tracking Control, Quasi-Static Feedforward Controller, Error-Based Proportional-Derivative Feedback Controller, Pantograph Scissor Lift Mechanism}
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To be successful in the digital era and advanced industries, the maintenance and optimal use of automatic equipment and machines are significant. Thus, the role of instrumentation equipment for correct measurement of the sensitive parameters in tools appears. Every organization needs high-precision measuring instruments to maintain its production quality. Besides, maintaining precision in measuring equipment requires controlling it by repeating its calibration. Accurate prediction of recalibration is significant because a short calibration interval increases the stopping time in the production line and the depreciation of measuring equipment. As a result, the increase in the stopping time can increase measurement uncertainties, causing other problems, such as quality loss in the production line. The present study aims to develop a method for timing the calibration of instrumentation equipment using Failure Modes and Effects Analysis (FMEA) and reliability, using the Risk Priority Number (RPN) and Reliability-Centered Maintenance (RCM) and via self-organizing map (SOM) neural network clustering. This method was implemented for 220 pieces of instrumentation equipment in the water supply system of Isfahan Zob Ahan Co. The research results show that this clustering leads to the change of calibration intervals and cost reduction in this part of Isfahan Zob Ahan Co.
Keywords: Calibration Intervals, Instrumentation Equipment, Failure Modes, Effects Analysis, Risk Priority Number, Reliability, Self-Organizing Map Neural Network Clustering, K-Means Algorithm. [1, 2]} -
Management information system (MIS), decision support system (DSS), and executive support system (EES) are the inevitable constituents of the intelligent systems which are being integrated with the infrastructural and technological development of the organizations to address non-routine decisions. The intelligent systems are incorporated with methodologies that support providing solutions to unpredicted decisions by employing mathematical and statistical tools and incorporating software programs embedded with cutting-edge algorithms. We investigate the applicability of several algorithms in the healthcare domain and propose mechanisms of development of machine learning techniques in the area of artificial intelligence. Artificial intelligence (AI) encompasses integer linear programming (ILP) and machine learning (ML) that further motivates us to dig up the algorithms and learning techniques to find the best solution in the field of predictive analytics for the supervised learning environments in correlating blood glucose concentration and hematocrit volume.
Keywords: Healthcare, AI, ML, Algorithms, Blood Glucose Monitoring System, Predictive Analytics, Deep Learning, Neural Network, Artificial Neural Network, Support Vector Machine} -
In this paper, a literature review on two-wheeled vehicle systems is methodically performed and presented. For this purpose, the principal aspects concerning the kinematic, dynamic, control, and identification features of articulated mechanical systems described within the multibody formulation approach are emphasized in this review article. First, the scientific investigations on two-wheeled vehicle modelling are chronologically described employing a historical literature review approach. This is done to set a consistent context for the subsequent developments analyzed in the paper. Then, following the systematic literature review methodology described in this work, a rich corpus of relevant documents in the time span between 2013-present. Moreover, bibliometric methods are used to construct the conceptual structure map of the research field, which also allowed for formulating a thematic classification. Thus, considering the full-texts of the identified corpus of documents, this work presents a synthetic analysis of the fundamental issues about the multibody approaches for modelling two-wheeled vehicles. Finally, future research perspectives are pointed out in this article
Keywords: Two-wheeled vehicles, Bicycles, Motorcycles, kinematics, dynamics of multibody systems, Nonlinear control, system identification, systematic literature review, bibliometric analysis} -
امروزه علاقه روز‌‌افزونی مبنی بر استفاده از رادار دهانه مصنوعی (SAR) در کاربرد آشکارسازی اهداف متحرک زمینی (GMTI) و تصویربرداری از اهداف متحرک زمینی (GMTIm) برای هر دو کاربرد نظامی و غیر نظامی وجود دارد.از آنجا که SAR برای تصویربرداری از صحنه ثابت طراحی شده است، تصویر SAR از هدف در حال حرکت مات و جابه‌جا می‌شود. از این‌رو برای به دست آوردن تصویر با وضوح بالا در این مقاله از یک الگوریتم جدید استفاده شده است که چارچوب آن مبتنی بر یادگیری بیزی تنک (SBL) است. برای ارزیابی کیفیت تصاویر، از نسبت هدف به کلاتر (TCR) و آنتروپی شانون استفاده شده است که معمولا برای ارزیابی تصویر رادار دهانه مصنوعی استفاده می‌شود. الگوریتم پیشنهادی TCR تصویر را در مقایسه با روش‌های متداول در حدود 10dB افزایش و آنتروپی تصویر را به مقدار 60%کاهش می‌دهد.
کلید واژگان: رادار دهانه مصنوعی (SAR), آشکارسازی اهداف متحرک زمینی (GMTI), تصویربرداری از اهداف متحرک زمینی (GMTIm), یادگیری بیزی تنک (SBL), توزیعLV ر, وش VB-EM}synthetic aperture radar (SAR) for ground moving target indication (GMTI) and imaging (GMTIm) have been gaining increasing interests for both civilian and military applications. Because SAR is generally designed for imaging a stationary scene, the SAR image of a moving target will be both displaced and smeared. More specifically, by exploiting the inherent sparsity of the moving targets in the clutter-suppressed SAR image domain, in this article. the intended SAR-GMTIm problem is solve by a sparse Bayesian perspective. The theory of CS has been successfully applied to SAR/ISAR imagery to achieve high cross-range resolution with a limited number of pulses In order to evaluate the quality of images, we apply the target-to-clutter ratio (TCR), which is commonly used in synthetic aperture radar (SAR) image assessment. The proposed algorithm shows a 10-dB higher TCR compared to the conventional algorithm.
Keywords: Synthetic Aperture Radar (SAR), Ground Moving Target Indication (GMTI) Ground Moving Target Imaging (GMTIm, Sparse Bayesian Learning(SBL), Lv’s Distribution (LVD), VB-EM} -
In this article, the thermal buckling behavior of orthotropic circular bilayer graphene sheets embedded in the Winkler–Pasternak elastic medium is scrutinized. Using the nonlocal elasticity theory, the bilayer graphene sheets are modeled as a nonlocal double–layered plate that contains small scale effects and van der Waals (vdW) interaction forces. The vdW interaction forces between the layers are simulated as a set of linear springs using the Lennard–Jones potential model. Using the principle of virtual work, the set of equilibrium equations are obtained based on the first-order shear deformation theory (FSDT) and nonlocal differential constitutive relation of Eringen. Differential quadrature method (DQM) is employed to solve the governing equations for simply-supported and clamped boundary conditions. Finally, the effects of the small scale parameter, vdW forces, aspect ratio, elastic foundation, and boundary conditions are considered in detail.Keywords: Thermal buckling, Bilayer graphene sheets, elastic medium, Nonlocal elasticity, van der Waals forces, First-order shear deformation theory, Differential quadrature method}
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In this paper, the numerical manifold method (NMM) with a 9-node quadrilateral element and a 10-node triangular element is developed. Furthermore, complex Fourier shape functions are used to improve the 9-node quadrilateral NMM. Also, the two approaches of higher-order NMM construction are compared, increasing the order of weight functions or local approximation ones; for this purpose, six-node triangular and three-node triangular using second-order and third-order NMM is used. For validation of the suggested method, one free vibration and two forced vibration numerical examples are assessed. The results show that the proposed methods are more accurate than conventional NMM. In addition, the superiority of complex Fourier shape functions compared to classical Lagrange ones in improving accuracy is perceived.Keywords: Numerical manifold method, Nine-node complex Fourier shape functions, Complex Fourier radial basis functions, Free vibrations, Forced vibrations, Ten-node shape functions}
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Today's parallel multipliers generally comprise three main parts: First is Partial Products Generator, which the most common method for this is to use Modified Booth Encoder (MBE) since it reduces the number of rows of an n bit multiplier to n/2+1 as well as executing signed multiplications. The second part is circuits that add Partial Products of equal value vertically to reduce the number of rows created in the first part into two rows. This part is generally done by Compressor or Counter. Finally, the third part is the final adder, which adds up the remaining two rows of the second part and produces the final multiplication outputs. Improvement in each of these 3 main parts can enhance the overall capacity of the multiplier. This paper presents a new high-speed 64x64-bit CMOS 8 stage pipelined Booth multiplier using fast booth encoder/decoder circuits, a new extra row elimination technique and a modified adder aiming to improve the speed of pipelined multiplier. In the proposed design, generation of first 31 bit rows and 32th row have the latency as low as 380 and 420 ps respectively due to optimizations in Booth Encoder/Decoder and first stage circuits. By applying these new architectures, the final adder performs 108-bit addition in only three cycles with high speed (2 GHz). With a 31% increase in the number of transistors and a 41% increase in latency, the multiplying sampling rate is 571% higher than the similar non-pipeline case. Power consumption @ 2GHz and 1.8 power supply is 924 mW. This multiplier is implemented in TSMC 0.18 µ CMOS technology and the results prove the effectiveness of the proposed method.
Keywords: Multiplier, Pipeline, Modified Booth, Carry-select Adder (CSA), Carry-lookahead Adder (CLA), Block Carry Generator, Sign- Extension, Extra Row Elimination} -
در این مقاله، مسئله کنترل توامان وضعیت و موقعیت نسبی فضاپیما درحضور عیب عملگر، مورد بررسی قرار گرفته است. پس از تبیین ضعف و محدودیت مدل‌های موجود و رویکردهای کنترلی مبتنی بر آن‌ها، صورت‌بندی جدیدی از حرکت نسبی فضاپیما ارایه گردیده است. آن‌گاه چارچوب کنترل پیش‌بین زیرفضاپایه، که یک رویکرد بدون مدل قدرتمند است، در ابعاد چندی گسترش داده شده است، که عبارتند از کنترل تطبیقی غیرخطی، تحمل‌پذیری نسبت به عیوب ناگهانی و تخصیص کنترل. بر اساس این چارچوب تعمیم یافته، سه کنترل‌کننده داده محور تحمل‌پذیر عیب مجزا برای کنترل فرآیندهای جفت‌شده، غیرخطی و متغیر با زمان، توسعه داده شده است. از منظر تشخیص عیب، تنها الزام ساختار کنترلی ارایه شده، آشکارسازی زمان وقوع عیوب است. به‌علاوه، یک قابلیت درونی تشخیص عیب داده محور معرفی گردیده است که ساختار کنترلی را کاملا خودبسنده خواهد نمود. کنترل‌کننده‌های سه‌گانه، سپس برای حل مسئله پیش‌گفته طراحی گردیده اند و کارایی آن‌ها از طریق یک سناریوی شبیه‌سازی چندبعدی، صحه‌گذاری گردیده است.
کلید واژگان: حرکت نسبی شش درجه آزادی فضاپیما, کنترل بدون مدل, کنترل پیش بین زیرفضاپایه, کنترل غیرخطی, کنترل تحمل-پذیر عیب, تخصیص کنترل, تشخیص عیب داده محور}The problem of jointly controlling relative attitude and position of spacecraft in the presence of actuator fault is investigated in this paper. Following a description about drawbacks and limitations of the existing models and the control approaches based on them, a new formulation of the spacecraft relative motion is provided. Subsequently, the subspace predictive control framework, which is a powerful model-free approach, is extended in several dimensions, that is, adaptive nonlinear control, tolerance against abrupt faults and control allocation. Based on this generalized framework, three distinct data-driven fault-tolerant controllers for coupled, nonlinear and time-variant plants are developed. From the viewpoint of fault diagnosis, the only requirement of the control structure is to detect the occurrence time of faults. Furthermore, an internal data-driven fault diagnosis capability is introduced, which makes the control structure completely self-sufficient. The three controllers are then designed to solve the aforementioned problem, and their efficiency are verified via a multidimensional simulation scenario.
Keywords: Spacecraft 6-DOF relative motion, Model-free control Subspace predictive control, Nonlinear Control, Fault-tolerant control, Control Allocation, Data-driven fault diagnosis} -
A branch of human knowledge, which treats the behavior of cracked structures, is called fracture mechanics. Since there is no intact structure in the world, then the paramount importance of fracture mechanics in human life is accentuated. The main parameter of fracture mechanics is called crack compliance, which is the amount of flexibility added to the flexibility of the intact structure due to the presence of a crack with specified size. The compliance, similar to flexibility, is the sole characteristics of the cracked structure. In this way for a given structure with a specified crack, there should be a single compliance. Unfortunately, in classical fracture mechanics that is not the case! The number of crack compliances for a clacked structure is equal to the number of researchers who treated the case! This diversity in the results stems from the presence of epistemic uncertainty in the mathematical basis of classical fracture mechanics. In view of the need for remedy, the Abdolrasoul Ranjbaran Team (ART), investigated the case and proposed a reliable fracture mechanics, which is based on sound logical reasoning. The proposed reliable fracture mechanics is described in the presented paper. The paper is managed via fourteen titles as, introduction, the mathematical basis of the classical fracture mechanics, birthplace of the state based philosophy, strong form of governing equation, analytical solution by Laplace transform, the weak form equation, the finite element equation, logical basis of the state based philosophy, state functions, Persian curves, reliable crack compliance, energy release rate, stress intensity factor, and weight function for the stress intensity factor in sections one to fourteen respectively. The paper concludes with a list of cited references.Keywords: Classical fracture mechanics, reliable fracture mechanics, State based philosophy, Persian Curves, flexibility, crack compliance, Stress intensity factor, energy release rate}
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The numerical results of mathematical modeling of a two-phase swirling turbulent flow in the separation zone of a centrifugal apparatus are presented. The motion of the carrier gas flow was modeled using the averaged Navier-Stokes equations, for the closure of which the well-known turbulence model by Schur and Spalart was used, the amendment to the Spalart-Allmaras SARC model. Based on the obtained field of averaged velocities of the carrier medium, taking into account turbulent diffusion. The article compares the results taking into account the influence of the solid phase on the dynamics of the air environment and without taking it into account with experimental data.Keywords: Reynolds-averaged Navier-Stokes equations, SARC model, Centrifugal air separator, current function, Vorticity, iteration, Eddy viscosity, Sweep, Upper relaxation}
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