Sharif Digital Repository

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 defective items produced in the first N cycles are accumulated at the end of the Nth cycle and are all reworked in a separate cycle called the rework cycle which has the same length as the other cycles and begins just at the end of the Nth cycle. At the end of the rework cycle the whole process will start all over again. For this system, assuming no shortages are permitted we obtain the economic batch quantity which minimizes the total cost  

In most real-world manufacturing systems, the production of goods comprises several autocorrelated stages and the quality characteristics of the goods at each stage are correlated random variables. This paper addresses the problem of monitoring a multivariate-multistage manufacturing process and diagnoses the possible causes of out-of-control signals. To achieve this purpose using multivariate time series models, first a model for the autocorrelated data coming from multivariate-multistage processes is developed. Then, a single neural network is designed, trained and employed to control and classify mean shifts in quality characteristics of all stages. In-control and out-of-control average... 

Determining the precedence of machining features is a critical issue in feature-based process planning. It becomes more complex when geometric interaction occurs between machining features. STEP-NC, the extension of STEP (ISO 10303) standard developed for CNC controllers, is a feature-based data model. It represents all the geometric and topological product data minus feature interactions. In this paper, machining precedence of interactive and non-interactive STEP-NC features is discussed. Local and global precedence of machining features are defined on the basis of geometric constraints, such as geometric interaction of features and feature approach face and technological constraint such as... 

The process of monitoring the events occurring in a computer system or network and analyzing them for sign of intrusions is known as intrusion detection system (IDS). The objective of this paper is to extract fuzzy classification rules for intrusion detection in computer networks. The proposed method is based on the iterative rule learning approach (IRL) to fuzzy rule base system design. The fuzzy rule base is generated in an incremental fashion, in that the evolutionary algorithm optimizes one fuzzy classifier rule at a time. The performance of final fuzzy classification system has been investigated using intrusion detection problem as a high-dimensional classification problem. Results show... 

Analogous to Computer-Aided Software Engineering (CASE), which aims to facilitate Software Engineering through specialized tools, Computer-Aided Method Engineering (CAME) strives to support a wide range of activities carried out by method engineers. Although there is consensus on the importance of tool support in method engineering, existing CAME environments are incomplete prototypes, each covering just a few steps of the method engineering process. This paper summarizes the history and the state of the practice in CAME technology, and provides criteria-based critique on existing CAME environments, thus highlighting their strengths and weaknesses. © 2008 Springer-Verlag Berlin Heidelberg  

In this paper, a comparative techno-economic evaluation of hydrogen production by glycerol reforming in aqueous and gaseous phases are presented. To accomplish the techno-economic evaluation, firstly the process modeling and design are presented. Based on the equipment purchased costs, with 80 kg/h hydrogen production, the total cost of hydrogen production is estimated 3.65 and 3.55 $/kgH2 for steam reforming and aqueous phase reforming plants, respectively. Regarding the installation factor in the equipment costs, the total cost of hydrogen production is estimated 7.49 and 7.45 $/kgH2 for steam reforming and aqueous phase reforming plants, respectively. To investigate the impact of... 

In this paper, the axiomatic design is introduced for designing the power electronic converters. The main idea of axiomatic design is to introduce variables affecting the desired performances of the system most independently possible. The design process is presented for a Buck converter. ©2008 IEEE  

Synthesis of the optimum conventional (with non-sharp separations) distillation column sequence (DCS) is a challenging problem, in the field of chemical process design and optimization, due to its huge search space and combinatorial nature. In this paper, a novel procedure for the synthesis of optimum Conventional Distillation Column Sequence is proposed. The proposed method is based on evolutionary algorithms. The main criterion used to screen alternative DCS's is the Total Annual Cost (TAC). In order to estimate the TAC of each DCS alternative all columns that exist in the DCS are designed using short-cut methods. The performance of the proposed method and other alternatives are compared... 

In this paper a strategic planning framework is proposed for generation expansion planning of grid-connected micro-power systems. The proposed framework is composed of two different decision making techniques that results a robust planning approach compared to previous techniques to identify the feasible and efficient plans according to attributes and uncertain parameters considered in planning environment. The framework considers the robustness and risk exposure of different configurations according to uncertain parameters in the planning environment to select the plans which meet the objectives more efficiently with least risk exposure. The proposed methodology is implemented for... 

Different processes in chemical industries deal with particles and multiphase flow. In such processes, particle or bubble size distribution (PSD) influences the final product quality and also process design. On the other hand, solutions to the dominant hydrodynamic and thermo-kinetic equations ignoring these distributions will make it impossible to accurately simulate these processes. Solutions to population balance equations (PBE's) are needed to attain the PSD. One of the most common methods for the solution of a PBE is the classes method (CM). However, as this method requires a large number of classes to give a reasonable result, it needs a huge amount of calculations and time. To... 

Scheduling models are one of the main parts of computer-aided process design research in recent years. One of the novel applications of scheduling models is their usage for in-site utility management of a process plant. It is very common for huge process plants to provide their utility by themselves; therefore, they shall make decision on utility supply and demand simultaneously. This approach can be extended to other similar systems such as distributed generation networks. In fact, it is possible to consider a DG unit as an autonomous system which is responsible for its energy (heat and power) supply and demand. Of course, for achieving its reliability and dispatchability goals, it would... 

Traffic assignment is one of the primary steps in the urban transportation planning process. There are several parameters that affect on drivers route choice. These factors arenot shown completely in the classic traffic assignment techniques so, these methodes donot have acceptable accuracy in the link volume estimating. Therefore many researchers have been tried to use fuzzy set theory in order to gain more precise approximation in traffic assignment. In this paper, we intend to propose a new fuzzy assignment model which has more flexibility relarive to driver behavior characteristics. At first, our assumptions are cited and then we illustrate how the membership function of the travel time... 

Human Brain is one of the most wonderful and complex systems which is designed for ever; A huge complex network composed of neurons as tiny biological and chemical processors which are distributed and work together as a super parallel system to do control and vital activities of human body. Brain learning simulation and hardware implementation is one of the most interesting research areas in order to make artificial brain. One of the researches in this area is Active Learning Method in brief ALM. ALM is an adaptive recursive fuzzy learning algorithm based on brain functionality and specification which models a complex Multi Input Multi Output System as a fuzzy combination of Single Input... 

This paper presents an efficient High-Level Synthesis (HLS) approach to improve RT-Level concurrent testing. The proposed method used for both fault detection and fault location. At first the available resources are used in their dead intervals to test active resources for fault detection, and then some changes are applied to the RT-Level controller to locate the faults. The fault detection step is based on a genetic algorithm (GA) search technique. This genetic algorithm is applied to the design after high level synthesis process to explore the test map. The proposed method has been evaluated based on dependability enhancement and area/latency overhead imposed to different benchmarks after... 

OMG's Model Driven Architecture (MDA) has deeply influenced modern-day software development, not only by providing promising means for automating the software process, but also through revitalizing the role of modeling in software development, the importance of which had been neglected during the recent euphoria over lightweight development methods. However, MDA's need to remain reasonably abstract means that it is more a software development approach rather than a standalone methodology, and therefore needs methodology support to be practically useful. Several MDA-based methodologies exist today, yet the need remains for the definition of an instantiable MDA-based development process. We... 

In this paper, we present an axiomatic modeling of lean production system design, using process variables (PVs). So far, we had developed a model for conceptual design of lean production systems by means of FR-DP relationships, the key characteristics of axiomatic design (AD) methodology, appeared in the proceedings of Second International Conference of Axiomatic Design. Albeit the model in question was thorough enough to be applied in various cases, its embedded abstract principles hamper straightforward applications and the required resources, tools, and techniques are not clarified. In AD terms, it lacks PVs created by mapping the design parameters (DPs) to the process domain to clarify... 

In this paper we present a novel approach for adjusting a multi band spectral subtraction filter coefficients based on speech recognition system results. Currently most speech enhancement techniques are designed according to various waveform level criteria such as maximizing SNR or minimizing signal error. However improvement in these criteria does not necessarily result in increasing speech recognition performance. Only if these methods generate sequence of features that maximize or increase the likelihood of the correct transcription relative to other incorrect competing hypotheses, speech recognition performance will increase. Here we use an utterance with a known transcription and... 

The continuing process of software systems enlargement in size and complexity becomes system design extremely important for software production. In this way, the role of software architecture is significantly important in software development. It serves as an evaluation and implementation plan for software development and software evaluation. Consequently, choosing the correct architecture is a critical issue in software engineering domain. Moreover, software architecture selection is a multicriteria decision-making problem in which different goals and objectives must be taken into consideration. In this paper, more precise and suitable decisions in selection of architecture styles have been...