DESIGN AND SIMULATION OF HIGH PRECISION SECOND-ORDER SIGMA-DELTA MODULATOR FOR BLUETOOTH APPLICATIONS

A second-order sigma-delta modulator is presented in this paper which, according to the considered standards, is suitable for bluetooth applications. The oversampling ratio and signal bandwidth of the proposed modulator is 128 and 1 MHz, respectively. The Signal to Noise and Distortion Ratio (SNDR) of the proposed structure is achieved 74 dB, equivalent to 12-bit accuracy, which is desirable precision for the aforementioned application. Utilizing highperformance blocks to implement the system at the circuit level, the sigma-delta modulator has obtained an overall desirable performance more specifically in terms of minimizing the power consumption. The modulator is simulated in 180 nm CMOS TSMC technology at cadence software applying 1.8 V supply voltage. The power consumption is obtained as low as 1.9 mW very suitable for portable modern ultra-low power applications

Radial variation of fiber dimenstions, annual ring width, and wood density from natural and plantation trees of Alder (Alnus glutinosa) wood

The aim of this research was to determine radial variations of some wood properties from natural and plantation trees of Alnus glutinosa. Oven-dried wood density (WD), fiber cell features, and annual ring width (ARW) were determined in radial positions of stem at breast height of tree. The results showed that the cultivation methods had significant influence on the fiber length (FL), fiber diameter (FD) and ARW. The effect of interaction between radial position and cultivation methods on anatomical features was not significant, except for cell wall thickeness (CWT). Fiber cell features and WD increased with distance from pith for both cultivations trees. The ARW decreased with increasing the cambial age in both cultivation methods. The average of FL and ARW in plantation trees was higher than those in natural trees. Widest FD was found in natural forest. There were significant relationships between ARW-WD and WD-FD for natural forest and between ARW-WD, ARW-CWT and WD-FL for plantation forest. About 67 % of WD variation in natural and plantation trees were related to FD and ARW, respectively. Due to high FL and ARW, wood from planted trees could be suitable for paper production than wood from natural trees

Demographics of Scorpion Sting in Iran; a Cross Sectional Study

Introduction: Scorpion sting is an important public health problem in some countries, including Iran. This study aimed to describe the demographics of a large number of these victims in some endemic areas of Iran.Methods: This cross-sectional study evaluated baseline characteristics, clinical findings, management, and disposition of scorpion stung cases in 26 cities of 4 provinces in the southwest quarter of Iran, during one year. Results: 3008 cases of scorpion sting with mean age of 27.07 ± 16.58 years were studied (51.3% female). The mean time from sting to hospital was 1.89 ± 1.04 hours. No first aid measures had been taken in 96.6% of cases. Lower (39.5%) and upper (35.7%) extremities were stung most frequently. Midnight to 6:00 am was the period of time most of stings occurred (34.2%). Local pain (77.2%) and erythema (63.5) were among the most common signs and symptoms. 2026 (67.3%) victims had been discharged; 326 (10.8%) were admitted or referred to other hospitals and 5 (0.2%) cases died.Conclusion: It seems that demographic characteristics of scorpion sting in Iran are not so different from those reported from other sites of the world, as signs and symptoms of local and systemic envenomations. Victims, companions, and healthcare providers perform many futile and maybe harmful measures and there is a need to educate all about all of these details

Dynamic optimization of methanol synthesis section in the dual type configuration to increase methanol production

International audienceThe main object of this research is dynamic modeling and optimization of the methanol synthesis section in the dual type configuration considering catalyst deactivation to improve methanol production capacity. In the methanol unit, deactivation of CuO/ZnO/Al2O3 catalyst by sintering and low equilibrium conversion of reactions limit the production capacity, and changing operating temperature is a practical solution to overcome the production decay. In the first step, the considered process is modeled based on the mass and energy balance equations at dynamic condition. To prove the accuracy of developed model, the simulation results are compared with the plant data at the same operating conditions. In the second step, a dynamic optimization problem is formulated, and the optimal trajectories of manipulated variables are determined considering methanol production rate as the objective function. Finally, the performance of optimized process is compared with the conventional system at the same design conditions. The results show that operating at the optimal conditions increases methanol production capacity about 6.45%

The effect of aquatic exercise on balance and gait characteristics of healthy elderly inactive men

Introduction: Aging process brings about various complications, which affect different aspects of elderly life. The purpose of this study was to study the effect of aquatic exercise on the balance and gait of healthy elderly inactive males. Materials and Methods: 30 healthy but physically inactive male volunteers, whose age were over 65 years and who had not participated in any exercise program before the initiation of the present study, were randomly assigned into experimental (mean age: 68.53 ± 1.98 years; mean weight: 69.45 ± 2.19 kg; mean height: 168.46 ± 3.08 cm) and control (mean age: 68.66 ± 2.78 years; mean weight: 72.60 ± 3.13 kg; mean height: 170.53 ± 3.14 cm) groups. The experimental group participated in a 6-week exercise program consisting of 3 sessions per week, each last for 60 minutes. Each exercise session included three main phases: a warm up, main exercise program and a cool down. The Sharpened Romberg Test, Star Excursion Balance Test and timed Up and Go were used to measure changes in balance and gait of subjects before the initiation and after the termination of the program. Obtained data were statistically analyzed via ANOVA and mixed multivariate of variance using SPSS software version 16. Significance level was set at P = 0.05. Results: No significant differences observed between pretest and post test scores in the control group (P ≥ 0/05). Significant improvements observed in balance and gait characteristics of the experimental group (P ≤ 0/05). Conclusion: The aquatic exercise program employed in this study resulted in considerable improvements in static and dynamic balance and gait abilities and also in the velocity of healthy elderly inactive men. Keywords: Aquatic exercise, Balance, gait, Healthy elderly inactive me

Opportunity domains: Invisible boundaries of entrepreneurial opportunities

Purpose: The purpose of the current paper is to provide a review of the researches on the most important typologies of entrepreneurial opportunities and to suggest an individual-based typology of entrepreneurial opportunities. Design/methodology/approach: The literature review method is used in the current paper to review the most important typologies of entrepreneurial opportunities and their contributions. Findings: Considering the three essential concepts of perceivability, exploitability, and desirability of entrepreneurial opportunities, this paper suggests an individual-based definition of the concept of entrepreneurial opportunity. In addition to the implications of the suggested framework for future studies and regarding its potential applications, the policies to move people from one domain of opportunity to another and also recommendations for entrepreneurs and investors are presented. Originality/value: This paper introduces the concept of opportunity domain, and suggests a three-level (domain) typology based on the role of individual(s) in identification and exploitation of entrepreneurial opportunities

Identification and Classification of Entrepreneurial Opportunities in Mobile Payment Services in Iran

With the advent of modern society and its increasing scope in global borders and consequently in Iranian society, consumption has attracted the attention of industrial activists as the central focus. In this regard, payment process as the heart of global trade has underlain the development and establishment of numerous technologies and businesses around this concept and caused a lot of efforts to be made for simplifying this process for consumers. After the experience of adopting the technologies associated with electronic payment, Iranian consumers have shown a lot of enthusiasm for the operation of mobile payment technologies. The increasing growth of penetration rate of mobile phones, smart cell phones, and mobile Internet has increased Iranian consumers’ interest in the use of these technologies. Hence, in the present study, using a qualitative approach and tacit knowledge of Iranian experts in mobile payment industry and also reviewing the global status of this industry, entrepreneurial opportunities of these services were identified and then classified in an applied framework for the use of activists in this industry

Morphometric study of the genus Erysimum L. (Brassicaceae) in Shomali, Razavi and Jonoubi Khorasan provinces

According to the “Flora Iranica”, the genus Erysimum has 26 species in Iran among which 11 species are reported in Shomali, Razavi and Jonoubi Khorasan provinces as yet. In this study, two of the species ate introduced for the first time. Due to the extreme similarities and the wide variation of the morphological characters, identification of these species is very difficult. In this study, we attempted to separate the species using morphological characters. We scored 75 morphological (vegetative and generative) characters of 84 individuals belonging to 11 species. The results of the multivariate analysis indicated the separation among the studied species and showed three distinct groups among samples. The first group was individuals of E. repandum, E. griffithianum, E. sisymbrioides, E. nanum and E. persepolitanum. The second group included individuals of E. aitchisonii, E. kerbabaevii and E. crassipes. The third group consisted of E. crassicaule, E. stocksianum, E. crassicaule (with trichome) and E. ischnostylum. Finally, an identification key was introduced based on morphological characters for Erysimum species in Khorasan

A taxonomic study on the genus Hymenocrater Fisch. & C. A. Mey. (Lamiaceae) in Khorasan region

The genus Hymenocrater (Lamiaceae, Mentheae) comprises 11 species in Flora Iranica of which nine species are mostly distributed in Iran. Among Iranian species, five are found in the Razavi, North and South Khorasan provinces. Eighty morphological characters were measured in 44 herbarium specimens belonging to: H. calycinus, H. bituminosus, H. platystegius and H. elegans. The Kruskal-Wallis Test was implemented to evaluate which characters significantly differentiate the species. Thus, forty-two morphological characters were used in subsequent analyses. Taxonomic relationships were investigated using the Principal Component Analysis (PCA). H. bituminosus and H. platystegius were separated in two distinct groups. There was no sharp distinction between the two other species, H. calycinus and H. elegans. Canonical discriminant analysis (CDA) was also applied to find the best discriminating traits among the species