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Bankruptcy Forecasting for Companies and Providing Counterfactual Scenarios to Change the Bankruptcy Class According to Financial Statement Data
, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
Bankruptcy is an important issue in the economy that can have extensive financial and social consequences on individuals and society. Timely warning to managers and providing analysis may prevent bankruptcy. Many studies have been conducted on the application and implementation of machine learning techniques to predict bankruptcy. Many bankruptcy prediction models produce incomprehensible outputs for the user. Therefore, they are called black box algorithms. Implementation of advanced models inevitably requires interpretability for users to understand the result and trust. Since most machine learning methods are "black box", explainable AI, which aims to provide explanations to users, has...
Adaptive control of regenerative chatter in turning process with tool wear effect
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Volume 10, Issue PART B , 2010 , Pages 1023-1030 ; 9780791843833 (ISBN) ; Moradi, H ; Vossoughi, G. R ; Alasty, A ; Movahhedi, M. R
2010
Abstract
Chatter suppression is of great importance for achieving high precision and surface quality in machining processes. A single degree of freedom model of orthogonal turning process is used to set up the nonlinear delay differential equation of motion. Tool wear effect is considered as the contact force between the workpiece and tool flank surfaces. Uncertainties in parameters of dynamic model and machining conditions are included in the model. An adaptive control strategy is applied for chatter suppression in cutting process. The force provided by a piezoactuator is the control input of the system. Results of stability analysis and adaptive control for two distinct cases of sharp and worn...
Spindle speed variation and adaptive force regulation to suppress regenerative chatter in the turning process
, Article Journal of Manufacturing Processes ; Volume 12, Issue 2 , August , 2010 , Pages 106-115 ; 15266125 (ISSN) ; Moradi, H ; Vossoughi, G ; Movahhedy, M. R ; Sharif University of Technology
2010
Abstract
Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this paper, two control strategies are developed to suppress chatter vibration in the turning process including a worn tool. In the first stage, a sinusoidal spindle speed variation around the mean speed is modulated to disturb the regenerative mechanism. The optimal amplitudes of the speed modulations are found based on a genetic algorithm such that the input energy to the turning process is minimized. In the second stage, to improve the response of the system which is associated with small ripples under the steady state condition, an adaptive controller is designed. In...
Spindle speed variation for regenerative chatter suppression in turning process with tool wear effect
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 4 , 2010 , Pages 619-626 ; 9780791849187 (ISBN) ; Vossoughi, G ; Rahaeifard, M ; Movahhedy, M ; ASME Turkey Section ; Sharif University of Technology
2010
Abstract
Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this paper, a single degree of freedom model of orthogonal turning process is used to set up the delay differential equation of motion with considering the tool wear effect as a contact force between the workpiece and tool flank surfaces. Sinusoidal spindle speed variations with different frequencies around the mean speed are modulated to disturb the regenerative mechanism. The optimal amplitudes of the speed modulations are found based on a genetic algorithm such that the input energy to the turning process is minimized. Results of the stability analysis and the...
Robust Control of Regenerative Chatter in Orthogonal Cutting Process with Spindle Speed and Feed Rate Variation
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholam Reza (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
During the turning operation, the interaction of the metal cutting process and machine tool causes a dynamic instability called self-excited vibration or chatter. Limited productivity rate, decrease in tool life, poor surface quality and noisy workplace are some adverse effects of the chatter vibration. Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this thesis, two control strategies are developed to suppress chatter vibration in turning process including a worn tool. A single degree of freedom model of the turning process including tool wear is briefly described. In the first stage, a sinusoidal spindle speed...
Performance control of a tape transport mechanism using entire eigenstructure assignment
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings, 13 November 2009 through 19 November 2009 ; Volume 10, Issue PART A , 2010 , Pages 133-140 ; 9780791843833 (ISBN) ; Haji Hajikolaei, K ; Motamedi, M ; Alasty, A ; Sharif University of Technology
2010
Abstract
To achieve high rate of data transfer, tape mechanisms must be able to transport the tape with a constant velocity for scanning. During this process, it is desired to make the rise time minimized without timing and data transfer errors. In this paper, three servo systems including the take-up and supply reel servos for tape tension control and capstan servo for speed control are considered. So, tape transport mechanisms can be described with a nonlinear multi-input multi-output system (MIMO). After state-space representation of the problem, feedback control is designed for tracking objective. It should be mentioned that an increase in the speed of time response of system corresponds to an...
Adaptive control of regenerative chatter in turning process with tool wear effect
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 10, Issue PART B , 2010 , pp. 1023-1030 ; ISBN: 9780791843833 ; Moradi, H ; Vossoughi, G. R ; Alasty, A ; Movahhedi, M. R ; Sharif University of Technology
2010
Abstract
Chatter suppression is of great importance for achieving high precision and surface quality in machining processes. A single degree of freedom model of orthogonal turning process is used to set up the nonlinear delay differential equation of motion. Tool wear effect is considered as the contact force between the workpiece and tool flank surfaces. Uncertainties in parameters of dynamic model and machining conditions are included in the model. An adaptive control strategy is applied for chatter suppression in cutting process. The force provided by a piezoactuator is the control input of the system. Results of stability analysis and adaptive control for two distinct cases of sharp and worn...
Optimal integrated inventory model with lost sale and backordering
, Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009, 6 July 2009 through 9 July 2009, Troyes ; 2009 , Pages 825-830 ; 9781424441365 (ISBN) ; Amiri Elyasi, K ; Save Shemshaki, A ; Sharif University of Technology
2009
Abstract
Rapid market changes, explosion of product varieties and short life cycleshave increased competition in today's global markets. It is obvious that intoday's competitive markets, collaboration between the vendor and the buyer isnecessary to reduce the joint inventory cost and the response time of thevendor-buyer system. Joint Economic Lot sizing Problem has been extended in manydifferent directions. Shortage is not allowed in the most of the previousresearches. A few of them considered shortage backordering as a result ofimperfect quality. The purpose of this paper is to recast the Joint economic lotsizing model to be more relevant to current situations, where lost sales and/orbackorders are...
Optimal Batch Production for a Single Machine System with Rework
, M.Sc. Thesis Sharif University of Technology ; Haji, Ali Reza (Supervisor)
Abstract
This research attempts to develop the optimal solution for an inventory problem consisting of a single machine which produces items some of which may be defective. We assume that no shortages are allowed and all defective items are to be reworked. Setup cost for rework and waiting time of defectives are considered. This research consists of two different parts. In the first part we consider two different policies where in the first policy in each cycle after the regular production the machine is setup for the rework of defectives of the same cycle. In the second policy several cycles constitute a period. All the defectives produced in the period are reworked in the last cycle of that period....
Stability analysis in multiwall carbon nanotube bundle interconnects
, Article Microelectronics Reliability ; Volume 52, Issue 12 , 2012 , Pages 3026-3034 ; 00262714 (ISSN) ; Faez, R ; Moravvej Farshi, M. K ; Sharif University of Technology
2012
Abstract
Based on the transmission line model (TLM), we present an exact and general transfer function formula, useful for both single multiwall carbon nanotube (MWCNT) and MWCNT bundle interconnects. Using the standard parameters for 22-nm technology node we perform the Nyquist stability analysis, to investigate the dependence of the degree of relative stability for both single and bundle interconnects on the number of walls in each MWCNT its geometry and also on the bundle geometry. The numerical results, for 1- to 30-μm long interconnects composed of 3- to 7-wall-CNTs, show that by increasing the length or the outer shell diameter, both single and bundle interconnects become more stable. On the...
Stability analysis in graphene nanoribbon interconnects
, Article IEEE Electron Device Letters ; Volume 31, Issue 12 , 2010 , Pages 1458-1460 ; 07413106 (ISSN) ; Moravvej Farshi, M. K ; Faez, R ; Sharif University of Technology
2010
Abstract
We present a Nyquist stability criterion based on transmission line modeling for graphene nanoribbon (GNR) interconnects. This is the first instance that such an analysis has been presented for GNR, so far. In this analysis, the dependence of the degree of relative stability for multilayer GNR (MLGNR) interconnects on the geometry of each ribbon has been acquired. It is shown that, increasing the length and width, MLGNR interconnects become more stable
A seamless-pitched graphene nanoribbon field effect transistor
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 74 , November , 2015 , Pages 414-420 ; 13869477 (ISSN) ; Moravvej Farshi, M. K ; Faez, R ; Sharif University of Technology
Elsevier
2015
Abstract
This paper proposes a graphene nanoribbon field effect transistor (GNRFET) consisting of pitched semiconducting GNRs as the channels that are connected to the metallic graphene source/drain in a seamless fashion. We obtained the diagrams for frequency bandwidths, step time responses, and Nyquist stability for the seamless pitched GNRFET (SP-GNRFET) with a channel having 100 pitched GNRs at 10 nm pitch in the common source configuration with various dimensions of the GNRs. The aforementioned diagrams were also obtained for the pitched carbon nanotube field effect transistor (CNTFET) with a channel having 100 pitched CNTs at 10 nm pitch in the common source configuration with various...
Optimal batch production with rework and non-zero setup cost for rework
, Article 2009 International Conference on Computers and Industrial Engineering, 6 July 2009 through 9 July 2009 ; 2009 , Pages 857-862 ; 9781424441365 (ISBN) ; Haji, R ; Haji, A ; Sharif University of Technology
2009
Abstract
This paper attempts to develop the optimal solution for an inventoryproblem consisting of a single machine which produces items some of which may bedefective. We assume that no shortages are allowed and all defective items areto be reworked. Setup cost for rework and waiting time of defectives areconsidered. We consider two different policies where in the first policy in eachcycle after the regular production the machine is setup for the rework ofdefectives of the same cycle. In the second policy several cycles constitute aperiod. All the defectives produced in the period are reworked in the last cycleof that period. At the end of the rework cycle the whole process starts allover again. One...
One-for-one period policy in a two-echelon inventory system with commoncycle and poisson demand rate for retailers
, Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009 ; 2009 , Pages 831-834 ; 9781424441365 (ISBN) ; Tayebi, H ; Haji, B ; Sharif University of Technology
2009
Abstract
This paper deals with a two-echelon inventory system consisting of onesupplier and N retailers. Each retailer faces an independent Poisson demand withthe same rate and applies a new ordering policy called one-for-one- periodordering policy for its inventory control. In this ordering policy the ordersize is equal to one and the time interval between any two consecutive ordersforms a common fixed cycle. Thus, the supplier faces a deterministic demand andadopts a deterministic inventory policy. At each cycle he orders a batch of sizeN to his own supplier. Upon receipt of each batch he sends 1 unit of theproduct to each retailer with a transportation cost. In this paper, for theabove system we...
Revenue sharing contract for a VMI with one for one period policy
, Article Cogent Engineering ; Volume 5, Issue 1 , 2018 , Pages 1-19 ; 23311916 (ISSN) ; Afzalabadi, M ; Haji, R ; Sharif University of Technology
Cogent OA
2018
Abstract
In this article, we design a revenue-sharing contract to coordinate inventory control decisions in a serial supply chain consisting of one supplier, one vendor, and one retailer. We assume that the retailer faces Poisson demand and his unsatisfied demands will be lost. The retailer applies one-for-one period policy in which he constantly places an order for one unit of product to the vendor in a predetermined time interval which results in a deterministic demand for the vendor. Vendor orders the required quantity from supplier which will be immediately received at the vendor’s warehouse. Solution procedures are developed to find the equilibrium in the vendor managed inventory program with a...
Pricing and inventory decisions in a vendor managed inventory system with revenue sharing contract
, Article Uncertain Supply Chain Management ; Volume 6, Issue 3 , 2018 , Pages 299-320 ; 22916822 (ISSN) ; Afzalabadi, M ; Haji, R ; Sharif University of Technology
Growing Science
2018
Abstract
In this paper, we design a revenue sharing contract to coordinate pricing and inventory control decisions in a serial supply chain consisting of one supplier, one manufacturer and one retailer. We assume that the retailer faces Poisson demand and his unsatisfied demands will be lost. The retailer applies one-for-one period policy in which he constantly places an order for one unit of product to the manufacturer in a predetermined time interval which results in a deterministic demand for the manufacturer. Solution procedures are developed to find the equilibrium in the Vendor Managed Inventory (VMI) program with a revenue sharing contract, in which no party is willing to deviate from for the...
Developing a partial backlogging deteriorating inventory model with selling price dependant demand rate and cycle length dependant selling price
, Article 2008 IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 2008, Singapore, 8 December 2008 through 11 December 2008 ; January , 2008 , Pages 198-202 ; 9781424426300 (ISBN) ; Sabahno, H ; Haji, R ; Sharif University of Technology
2008
Abstract
In this paper, we develop an inventory model with price dependant demand rate, under time value of money and inflation, finite time horizon, exponential backlogging rate and exponential deterioration rate with the objective of maximizing the present worth of the total system profit. Using a dynamic programming based solution algorithm, we are able to find the optimal sequence of the cycles and also to obtain different optimal selling prices and optimal order quantities for the cycles with unequal lengths, which have never been done before for our model. We also use a proper numerical example to show accuracy of the solution procedure. © 2008 IEEE
A developed distance method for ranking generalized fuzzy numbers
, Article Neural Computing and Applications ; 2014 , pp. 1-5 ; ISSN: 09410643 ; Zare, H. K ; Eslamipoor, R ; Sepehriar, A ; Sharif University of Technology
2014
Abstract
Fuzzy logic is one of the effective tools to handle uncertainty and vagueness in engineering and mathematics. One major part of fuzzy logic is ranking fuzzy numbers. In many fuzzy program systems, ranking fuzzy numbers has a remarkable role in decision making and data analysis. Despite the fact that a variety of methods exists for ranking fuzzy numbers, no one can rank fuzzy numbers perfectly in all cases and situations. In this paper, a new method for ranking fuzzy numbers based on the left and right using distance method and α-cut has been presented. To achieve this, a fuzzy distance measure between two generalized fuzzy numbers is proposed. The new measure is expanded with the help of the...
One-for-one period policy and a series of suppliers
, Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009, 6 July 2009 through 9 July 2009, Troyes ; 2009 , Pages 902-906 ; 9781424441365 (ISBN) ; Pirayesh Neghab, M ; Haji, A ; Sharif University of Technology
2009
Abstract
The purpose of this paper is to adopt and analyze a new ordering policycalled one-for-one-period policy in a multi-echelon supply chain consisting ofone retailer and a series of TV suppliers. The main advantage of adopting theone-for-one-period (7,7) ordering policy for retailers is the elimination ofuncertainty for supplier which leads to total elimination of the safety stocksat all suppliers. This in turn leads to the reduction of the total system costsand in case any supplier's ordering cost is negligible it can even eliminate theneed for him to carry any inventory. In addition to this advantage, thenumerical results show that the application of this new policy for the retailerleads to...
Optimal batch production with minimum rework cycles and constraint on accumulated defective units
, Article 2009 IEEE/INFORMS International Conference on Service Operations, Logistics and Informatics, SOLI 2009, Chicago, IL, 22 July 2009 through 24 July 2009 ; 2009 , Pages 633-638 ; 9781424435418 (ISBN) ; Haji, A. R ; Haji, R ; Sharif University of Technology
2009
Abstract
This paper deals with the issue of economic batch quantity (EBQ) in a single machine system in which defective items are produced in each cycle of production. The accumulated defective items produced in a period, consisting of several equal cycles, are all reworked in the last cycle of this period called the rework cycle. At the end of each period the whole process will start all over again. We assume that there is a limitation on the total defective items. We also do not adopt the restriction that the rework process rate be equal to the normal production rate. In addition we assume that there is a set up time for rework process. Further we assume that the number of rework cycles be as small...