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مرکز اطلاعات علمی SID1
اسکوپوس
دانشگاه غیر انتفاعی مهر اروند
ریسرچگیت
strs
Author(s): 

WANG C. | CHEN Z.W. | CHEN G.Y.

Journal: 

SCIENTIA IRANICA

Issue Info: 
  • Year: 

    2014
  • Volume: 

    21
  • Issue: 

    3 (TRANSACTIONS B: MECHANICAL ENGINEERING)
  • Pages: 

    628-646
Measures: 
  • Citations: 

    0
  • Views: 

    97832
  • Downloads: 

    71686
Abstract: 

This paper is concerned with the problem of Delay-dependent passive analysis and control for interval stochastic time-Delay systems. The system matrices are assumed to be uncertain within given intervals, the time Delay is a time-varying continuous function belonging to a given range, and the stochastic perturbation is in the form of a Brownian motion. By using ItO's differential formula and the Lyapunov stability theory, Delay-dependent stochastic passive control criteria are proposed without ignoring any useful terms by considering the information of the lower bound and upper bound for the time Delay. Based on the criteria obtained, a Delay-dependent passive controller that ensures the stochastic passivity of the closed-loop system is presented. Then, the controller gain is characterized in terms of LMIs, which can be easily checked by resorting to available software packages. Numerical examples are given to demonstrate the effectiveness of the method.

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Author(s): 

MOAZEDI MARYAM

Issue Info: 
  • Year: 

    2020
  • Volume: 

    1
  • Issue: 

    3
  • Pages: 

    23-34
Measures: 
  • Citations: 

    0
  • Views: 

    297
  • Downloads: 

    145
Abstract: 

Supporting the highest bandwidth data rates among new generation of communication devices requires advanced clock management technology such as DL (Delay Line). By introducing object internet increase of the system clock frequency poses some challenges in generating and distributing of the clock with low uncertainty and power, as clocks determine the overall performance of the chip. The generated signal quality determines by several factors as frequency, phase, period, jitter and clock variations. Both analog and digital circuits have some limitations which make it impossible to achieve high quality clock. One of the proposed solutions for performance improvement of DLs is the utilization of both analog and digital circuits in one system. In this thesis a low jitter and wide operation range Mixed-Mode Delay Line presented. Body feed technique and proper bias circuit are used in the proposed multiphase Mixed Controlled Delay-Line (MMCDL) to widen applicable range of control voltage, allow rail-to-rail operation and overcome the nonlinearity of the conventional current starved Delay element. Furthermore, two single ended current starved inverters are utilized in a differential structure to minimize the effect of the power supply and the substrate noise. In this way jitter and static phase error specifications are improved. The designed circuit is simulated in ADS software, using TSMC 0. 18 um CMOS process at 1. 8V supply voltage. Simulation outcomes indicate that the frequency range of the suggested DL is 80-920 MHz. The rms jitter and power dissipation of the designed circuit at 920 MHz are 3. 7psec and 3. 9 mW respectively.

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Author(s): 

VALI A.R. | NIK RAVESH S.K.Y.

Journal: 

SCIENTIA IRANICA

Issue Info: 
  • Year: 

    2007
  • Volume: 

    14
  • Issue: 

    6
  • Pages: 

    586-590
Measures: 
  • Citations: 

    0
  • Views: 

    107137
  • Downloads: 

    57151
Keywords: 
Abstract: 

In this paper, a new approach for constructing quadratic Lyapunov-Krasovskii functionals for a class of nonlinear time-Delay systems is developed. The functionals are then used to derive Delay dependent stability conditions. These conditions are sufficient and local. Numerical example shows that the results obtained using the proposed method is less conservative than those obtained by the existing methods.

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گارگاه ها آموزشی
Issue Info: 
  • Year: 

    2003
  • Volume: 

    16
  • Issue: 

    2 (35)
  • Pages: 

    18-28
Measures: 
  • Citations: 

    0
  • Views: 

    11183
  • Downloads: 

    179
Abstract: 

Statement of Problem: Recently, investigators have presented new methods to reduce polymerization shrinkage of composite resin restorations. It is claimed that more powerful light cure systems associated with a change in radiation patterns, lead to improved mechanical properties and reduced microleakage. Purpose: The aim of the present study was to evaluate the effects of two curing systems, known as Soft- Start, Pulse-Delay, on microleakage and degree of conversion of composite resin restorations. Materials and Methods: To evaluate microleakage, dye penetration method in class V cavities was applied. 30 extracted human molars filled with three different curing techniques, namely conventional, Soft-Start and Pulse-Delay, were compared. Degree of conversion was measured by FTIR Spectroscopy method immediately after sample curing. Kruskal- Wallis and Mann-Whitney test were used to compare groups. Results: The degree of microleakage in enamel and dentin among three groups was not significantly different, however, microleakage in gingival and occlusal walls showed a significant difference among Pulse-Delay curing (P=0.001) and Soft-Start curing (P=0.28) groups, meaning that leakage gingival in wall was significantly higher than occlusal wall. This difference was not significant in conventional group. Moreover, the degree of conversion was not statistically significant among three groups (P=0.909). Conclusion: Soft-Start and Pulse-Delay curing systems, with a two intensity start curing light, do not provide better marginal adaptation in class V composite resin restorations. It should be mentioned that polymerization degree is not also reduced in these methods.

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Author(s): 

Moradi Elahe

Journal: 

JOURNAL OF CONTROL

Issue Info: 
  • Year: 

    2020
  • Volume: 

    14
  • Issue: 

    2
  • Pages: 

    79-87
Measures: 
  • Citations: 

    0
  • Views: 

    106
  • Downloads: 

    132
Abstract: 

In this paper, the problem of finite-time stability and finite-time stabilization for a specific class of dynamical systems with nonlinear functions in the presence time-varying Delay and norm-bounded uncertainty terms is investigated. Nonlinear functions are considered to satisfy the Lipchitz conditions. At first, sufficient conditions to guarantee the finite-time stability for time-Delay nonlinear system with uncertainties and based on the Lyapunov approach is presented. In the following, sufficient conditions to ensure finite time stabilization the considered system with state feedback are presented. In the proofs of proposed theorems are used from the appropriate Lyapunov-Krasovskii function and newton-Libniz-formula that can reduce the conservative. Also, all of the obtained conditions in this paper are Delay-dependent and presented as linear matrix inequalities. Finally, the numerical examples and simulations exhibit the effectiveness of the proposed methods.

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Issue Info: 
  • Year: 

    2001
  • Volume: 

    44
  • Issue: 

    71
  • Pages: 

    116-118
Measures: 
  • Citations: 

    0
  • Views: 

    669
  • Downloads: 

    129
Abstract: 

We have studied 47 patients who had macroscopic Hematuria. All of these patients have had TUR P at least one year ago.We evaluated them for etiologic cause of hematuria with physical examination, Urine Analysis, urine culture and ultrasonografy. We found that the most common cause was Recurrent of "B.P.H." and second cause was infection.

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strs
Issue Info: 
  • Year: 

    2012
  • Volume: 

    21
  • Issue: 

    82
  • Pages: 

    65-70
Measures: 
  • Citations: 

    0
  • Views: 

    590
  • Downloads: 

    235
Keywords: 
Abstract: 

Introduction: Orthopedic tumors are most commonly seen in the young adults. Treatment Delay in these important entities could have significant adverse effects on human communities.Objective: Our goal in this review is the evaluation of patients with benign and malignant orthopedic tumors to identify the main causes of Delay in the presentation and treatment of such tumors.Materials and Methods: In this cross sectional study, we evaluated cases with potentially important orthopaedic tumors from December 2008 to June 2010. Treatment Delay was divided into two parts; (1) patient Delay, and (2) physician Delay. In identifying the patient Delay, the respective declaration was noted but in exploring the main causes of physician Delay, the time to get complementary imaging or laboratory exams and in some cases interview with the primary physician were taken into account.Results: We studied 200 cases (108 males and 92 females) with a mean age of 27.4 years, ranged 6 to 62 years. The median patient and physician Delay was 8 months (ranged 0.5 to 120) and 4 months (ranged 0.5 to 84), respectively. Total median treatment Delay was 12 months. The most common cause of patient and physician Delay was assuming trivial the early symptoms of tumor and not timely complementary imaging, accordingly.Conclusion: Public education about early symptoms of orthopedic tumors and promotion of general practitioners’ knowledge to follow timely and proper use of complementary imaging seem to have significant effects on reducing the treatment Delay in these tumors.

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Author(s): 

ZOKAEE ASHTIANI H. | MAZLOMI E.

Issue Info: 
  • Year: 

    2006
  • Volume: 

    22
  • Issue: 

    33
  • Pages: 

    31-36
Measures: 
  • Citations: 

    0
  • Views: 

    1723
  • Downloads: 

    423
Keywords: 
Abstract: 

Delay at intersections constitutes a major part of travel time in urban networks. Nevertheless, in traffic assignment models, intersection Delay is either ignored or assumed constant, due to difficulties in considering the Delay for one approach as a function of various conflicting approach traffic volumes, as well as lack of appropriate functions to measure the Delay. In this paper, by using the data which has been collected from five intersections in the city of Tehran, two types of Delay function are presented which are, not only dependent on the traffic light setting and the approaching traffic volume, but, depend on the traffic volume in conflicting approaches.Moreover, based on the data collected in a signalized intersection which was previously unsignalized, the effect of traffic light installation on an unsignalized intersection is closely studied. Finally, two actuated signalized intersections are examined to see the effect of installed actuated traffic light systems upon intersection Delay.

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Issue Info: 
  • Year: 

    2008
  • Volume: 

    51
  • Issue: 

    99
  • Pages: 

    37-40
Measures: 
  • Citations: 

    0
  • Views: 

    654
  • Downloads: 

    258
Abstract: 

Introduction: The incidence of pulmonary tuberculosis in our region is high. Despite the recent advances in medicine, still many patients suffer from longstanding tuberculosis. Delay in diagnosis may result in further morbidity and mortality. So, the goal of this study to evaluate the patient Delay and physician Delay.Materials and Methods: A descriptive study was done from 2004 to 2007 at Imam Reza Hospital on 86 patients with pulmonary tuberculosis. Those patients who fulfilled the inclusion criteria undervent a face to face interview and then the questioner's checklist was filled out. The interval between the first appearance of the clinical manifestation and first visit to the physician was considered the patient Delay and the period between the patient's first visits to the final diagnosis was the physician's Delay. Gathered data was analyzed with analyctic methods and T test.Result: The mean patient Delay time was 14.69±10.91 with a median of 12.5 days. The mean physician Delay time was 84.30±42.75 with a median of 80 days. The mean total Delay time was 99±44.70 days with a median of 92.50 days.Conclusion: According to this study the patient Delay in our region is acceptable in comparison with other studies, but our physician Delay was long. Thus improving and upgrading the mycobacteriological courses for general physicians and specialists is recommended.

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Author(s): 

LOTFI M.H. | ALLAMI A.

Issue Info: 
  • Year: 

    2017
  • Volume: 

    21
  • Issue: 

    1 (90)
  • Pages: 

    74-78
Measures: 
  • Citations: 

    0
  • Views: 

    546
  • Downloads: 

    228
Abstract: 

Early diagnosis of meningitis and encephalitis and prompt initiation of appropriate therapy is vital and any Delay will lead to high mortality and serious and permanent morbidity. The main purpose of this study was to evaluate the management of 220 patients with suspected central nervous system (CNS) infections (meningitis and encephalitis) to determine the percentage of patients’ suspected CNS infection undergo lumbar puncture in acceptable time (in accordance with conventional algorithms). In this descriptive study, patients with suspected CNS infections admitted to Bu-Ali and Qods hospitals, in the period July 2013 to December 2015 were studied. Information of 220 patients was collected. Continuous variables were summarized as means±standard deviation and categorical variables as frequencies and percentages. Lumbar puncture (LP) in patients was Delayed in 200 cases (91%). Most common causes of Delay in performing LP were prolongation of the process of determining patient needs to puncture, satisfying patients, CT scan Delay and the Delay in allowing LP by neurologist. In this study, Delaying LP rate was higher than other studies. It seems certain pattern in assistants’ visits for counseling. CT requests and neurologic consultation before LP performed for all adult patients.

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