Sharif Digital Repository

One of the roles of a Natural Language Processing (NLP) model in Continuous Speech Recognition (CSR) systems is to find the best sentence hypothesis by ranking all n-best sentences according to the grammar. This paper describes a robust parsing algorithm for Spoken Language Recognition (SLR) which utilizes a technique that improves the efficiency of parsing. This technique integrates grammatical and statistical approaches, and by using a best-first parsing strategy improves the accuracy of recognition. Preliminary experimental results using a Persian continuous speech recognition system show effective improvements in accuracy with little change in recognition time. The word error rate was... 

Accidents involving falls and falling objects (group I) are highly frequent accidents in the construction industry. While being hit by a vehicle, electric shock, collapse in the excavation and fire or explosion accidents (group II) are much less frequent, they make up a considerable proportion of severe accidents. In this study, multiple-correspondence analysis, decision tree, ensembles of decision tree and association rules methods are employed to analyse a database of construction accidents throughout Iran between 2007 and 2011. The findings indicate that in group I, there is a significant correspondence among these variables: time of accident, place of accident, body part affected, final... 

This paper addresses the multiple allocation hub set-covering problem considering backup coverage and mandatory dispersion of hubs. In the context of this paper, it has been assumed that a flow is covered if there are at least Q possible routes to satisfy its demand within a time bound. Moreover, there is a lower limit for the distance between hubs in order to provide a degree of dispersion in the solution. Mathematical formulation of this problem is given, which has O( n2) variables and constraints. Computational experiments carried out on the well-known CAB dataset give useful insights concerning model behavior and its sensitivity to parameters  

The maximal covering location problem (MCLP) is a challenging problem with numerous applications in practice. Previous publications in the area of MCLP proposed models and presented solution methodologies to solve this problem with up to 900 nodes. Due to the fact that in real-life applications, the number of nodes could be much higher, this paper presents a customized Genetic Algorithm (GA) to solve MCLP instances, with up to 2500 nodes. Results show that the proposed approach is capable of solving problems with a fair amount of exactness. In order to fine-tune the algorithm, Tukey's Least Significant Difference (LSD) tests are employed on a set of test problems  

Fuzzy functions are used to identify the structure of system models and reasoning with them. Fuzzy functions can be determined by any function identification method such as Least Square Estimates (LSE), Maximum Likelihood Estimates (MLE) or Support Vector Machine Estimates (SVM). However, estimating fuzzy functions using LSE method is structurally a new and unique approach for determining fuzzy functions. By using this approach, there is no need to know or to develop an in-depth understanding of essential concepts for developing and using the membership functions and selecting the t-norms, co-norms and implication operators. Furthermore, there is no need to apply fuzzification and... 

Air–water flow is a complex and challenging subject in many engineering fields as well as hydraulic engineering; and discovery of its characteristics can help the engineers to predict and analyze a probable phenomenon. In the present paper, development of a device capable of measuring the flow velocity, air concentration, diameter and counts of bubbles in air–water flows is described. The heart of the present device is two resistive probes with a novel configuration. Being pressure and corrosion resistant and also having negligible resistivity in the flow are some of the unique features of the employed needles. Moreover, sampling frequency and time can be adjusted for the intended... 

In this paper, several numerical simulations are performed to study the failure of epoxy adhesive joining composite plates. Different geometries for the joint and its edge are considered, and the effects of these geometries on the failure load are investigated. Moreover, the joints are subjected to different types of loading in order to determine the failure load. The failure theories of composite materials are implemented into the finite element software ABAQUS, and the failure propagation in the joint is studied. © 2020, Shiraz University  

A Hub Location Problem (HLP) deals with finding the locations of hub facilities and assignment of demand nodes to established facilities. Hubs play a central role in many networks such as telecommunication networks and their unavailability may lead to network breakdown or poor service levels. An objective in design of a hub-and-spoke network is maximization of reliability to transfer flows. This paper puts forward design of a reliable single-allocation hub-and-spoke network using an interactive fuzzy goal programming. To model and solve the problem, a fuzzy goal programming approach was developed for design of network in an interactive manner between decision maker and the model. To validate... 

This paper presents a comprehensive design procedure of a brushless DC limited angle torque motor (LATM) based on magnetic equivalent circuit analysis which predicts its performance and magnetic characteristics. Design of toroidally wounded armature and rotor with two pole tip segments are developed using selected ferromagnetic material and rare earth permanent magnets. Derivation of airgap and other motor dimensions and design parameters with their expressions are given. A finite element analysis verification of designed LATM using a 2D modeling and simulating package is presented. Performance characteristic of analytical model and FEA model of designed LATM is compared which validates the... 

Most of the publications regarding the maxim covering location problem (MCLP) address the case where the decision is to be made for one period. In this paper, we deal with a rather untouched version of MCLP which is called dynamic MCLP (DMCLP). In order to solve this problem, a simulated annealing (SA) has been presented. The proposed solution algorithm is capable of solving problems with up to 2500 demand nodes and 200 potential facilities with a fair amount of exactness. Our experiments showed that the proposed approach finds solutions with errors less than one percent  

In this paper, a new cache placement scheme is proposed to achieve higher hit ratios with respect to the two conventional schemes namely set-associative and direct mapping. Similar to set-associative, in this scheme, cache space is divided into sets of different sizes. Hence, the length of tag fields associated to each set is also variable and depends on the partition it is in. The proposed mapping function has been simulated with some standard trace files and statistics are gathered and analyzed for different cache configurations. The results reveal that the proposed scheme exhibits a higher hit ratio compared to the two well-known mapping schemes, namely set-associative and direct mapping,... 

This paper presents a quadrature-clock generator based on a novel low-power ring oscillator with a wide frequency tuning range and low temperature variations. The proposed ring oscillator consists of two differential delay cells with a new controllable capacitive load of an MOS transistor. The wide tuning range is achieved due to transistor utilization in different regions and considering its resistance not to narrow down the frequency range. Delay cells are biased with a minimum possible value of a proportion to absolute temperature current to decrease frequency variations to temperature while the power consumption is kept low. The validation of the proposed methods is proved by circuit... 

This paper presents a new cache scheme based on varying the size of sets in the set-associative cache hierarchically. In this scheme, all sets at a hierarchical level have same size but are fc times more than the size of sets in the next level of hierarchy where k is called division factor. Therefore the size of tag fields associated to each set is variable and it depends on the hierarchy level of the set it is in. This scheme is proposed to achieve higher hit ratios with respect to the two conventional schemes namely set-associative and direct mapping. The proposed scheme has been simulated with several standard trace files SPEC 2000 and statistics are gathered and analyzed for different... 

This paper presents two effective methods to reduce power consumption of branch target buffer (BTB): 1) the first method is based on storing distance to next branch address in tag array instead of storing whole branch address, 2) the second method is to use a new field in data array of BTB namely Next Branch Distance (NBD) which holds distance of next branch address from current branch address. When a new hit is performed in BTB, based on NBD field, there would be no access through NBD number of instructions, so BTB can be shutdown not to consume power. The new architecture does not impose extra delay and reduction in prediction accuracy. Both methods were implemented and simulated using... 

This paper presents two effective methods to reduce power consumption of branch target buffer (BTB): 1) the first method is based on storing distance to next branch address in tag array instead of storing whole branch address, 2) the second method is to use a new field in data array of BTB namely Next Branch Distance (NBD) which holds distance of next branch address from current branch address. When a new hit is performed in BTB, based on NBD field, there would be no access through NBD number of instructions, so BTB can be shutdown not to consume power. The new architecture does not impose extra delay and reduction in prediction accuracy. Both methods were implemented and simulated using... 

The current study presents a numerical investigation on turbulent hydrothermal characteristics in a wavy passage equipped with discontinuous twisted tapes. The working fluid is water and passage walls are kept under constant wall temperature. The effect of Reynolds number (Re = 2500, 4500, 6500, 8500 and 10500), twist angle (TA = 90∘ and 180∘) and inclination angle (IA = 15∘ and 30∘) on velocity fields and streamlines, temperature contours, Nusselt number, friction factor, turbulent kinetic energy (TKE), thermal performance factor (TPF), energy efficiency factor (EEF) and entropy generation rate are evaluated. More uniform temperature and velocity fields can be found as both wavy passage and... 

Dependability evaluation of embedded systems due to the integration of hardware and software parts is difficult to analyze. In this paper, we have proposed an experimental method to determine sensitivity to soft errors in an embedded system exploiting Altera SRAM-based FPGAs. The evaluation is performed using both the hardware and software parts of the embedded system in a single framework. To do this, the HDL hardware model of the target system as well as the C-written software codes of the target system, are required. Both permanent and transient faults are injected into the partially- or fully-synthesizable hardware of the target system and this can be performed during the design cycle of... 

Caches, which are comprised much of a CPU chip area and transistor counts, are reasonable targets for transient single and multiple faults induced from energetic particles. This paper presents: (1) a new fault detection scheme for tag arrays of cache memories and (2) an architectural cache to improve performance as well as dependability. In this architecture, cache space is divided into sets of different sizes and different tag lengths. Using the proposed fault detection scheme, i.e., GParity, when single and multiple errors are detected in a word, the word is rewritten by its correct data from memory and its GParity code is recomputed. The error detection scheme and the cache architecture... 

SRAM cache memories suffer from single event upset (SEU) faults induced by energetic particles such as neutron and alpha particles. To protect these caches, designers often use error detection and correction codes, which typically provide single-bit error detection and even correction. However, these codes have low error detection capability or incur significant performance penalties. In this paper, a protected cache scheme based on the variable associativity of sets is presented. In this scheme, cache space is divided into sets of different sizes with variable tag field lengths. The other remained bits of tags are used for protecting the tag using a new protection code. This leads to... 

The size and speed of SRAM caches of embedded systems are increasing in response to demands for higher performance. However, the SRAM caches are vulnerable to soft errors originated from energetic nuclear particles or electrical sources. This paper proposes a new protected cache scheme, which provides high performance as well as high fault detection coverage. In this scheme, the cache space is divided into sets of different sizes. Here, the length of tag fields associated to each set is unique and is different from the other sets. The other remained bits of tags are used for protecting the tag using a fault detection scheme e.g., generalized parity. This leads to protect the cache without...